Coral or Sponge; a process of identification

Sponge or Coral (Mystery Florida Fossil)

Sponge or Coral (Mystery Florida Fossil)

I’ve been very perplexed by this fossil, but my tenacious curiosity doesn’t give up easily.  Follow along as I finally come to a conclusion.  To begin with, the mystery fossil  possesses obvious meandering ridges resembling the various brain type corals I’ve observed from my Florida collection, yet it possesses numerous deeply pitted openings very much like the encrusting  sponge species below, also known to be found in Florida.

Florida Brain Coral Fossil

Florida Brain Coral Fossil

The problem with the encrusting type of sponge is that they cover a hard surface such as corals or rocks much the same way in which moss covers the ground.  I don’t know enough about sponges to understand if this type of growth pattern would break loose and end up on a beach where my mother-in-law, Winkie, picked it up during the 70′s and 80′s.

Rose Brain Coral Fossil

Rose Brain Coral Fossil

 

 

 

 

 

 

 

 

 

 

 

 

If you’ll notice, the “rose brain coral” above has a few pitted holes like the mystery fossil; and if you’ll also notice, the “pink lumpy sponge” possesses a pattern of ridges, but only sort of like it.  Hmmmm . . . a point I’d like to make for a second is that’s how fossil hunters learn to observe things as discriminately as they do in order to identify their findings.

So, anyway, we’re on the bloodhound trail, let’s continue observing.  On the one hand, the mystery fossil is quite lighter and airier compared to the other Florida corals in my collection and it has more openings visible on all sides which also leads me to think it could be a sponge.  Only, the patterns of the openings are similar in shape and size as other coral. I don’t see any distinct differences at any rate.  The overall color and texture is consistent with the other corals as well.

 

Tube Worms On Clam

Tube Worms On Clam

 

 

 

 

 

 

 

 

 

 

 

 

In conclusion, if the mystery fossil on most levels appears to be a coral, except mostly for the deep pitted holes, what could have caused those holes and why so many, if indeed it’s not a sponge.  You’ve most likely already guessed from the photos of  the tube worms above.  The clam fossil with the tube worm shells embedded on top of it came from the same Florida collection. The Christmas tree tube worms in the other photo demonstrates how they can dominate the surface of coral.  I’m no expert, but I decided the mystery fossil is a type of brain coral which was apparently under attack from several tube worms of one type or another.  Feel free to disagree in the comments if you know of think otherwise.

Check out the tube worms link to the right listed under CLASSIFICATIONS to learn more about them and how they can actually be quite pretty.

Coral Sponge

Florida Sponge Fossil

Florida Sponge Fossil

 

The title “Coral Sponge” refers to the coral color of this sample and because I’m 90% certain it’s a sponge and not a coral skeleton/fossil. The main reason is because of the lack of vertical septa walls inside the cups, or in the case of sponges, pores. You can click on the image above to enlarge and observe its finer details. (If you believe it’s not a sponge, feel free to comment)

septa3

Coral cups showing septa (walls)

 

There are some 5,000 to 10,00 known species of sponges and identification usually depends on the patterns and shapes of their spicules (tiny rods used for defense) often only visible enough through the microscope in order to distinguish.

In lieu of this, I can only wager a guess as to its exact identity. It’s a rather attractive piece from my mother- in-law’s collection she gathered in the 70′s and 80′s off Florida beaches. So, I’m guessing it’s some kind of calcareous type which forms a hard calcium carbonate skeleton; and I would also say that it’s a tube type of some kind.

 

Below, I found a tube type of sponge from a Florida reef. It looks fairly close in comparison. See what you think . . .

 

 

Tube Coral Sponge (Reverse Side)

Tube Coral Sponge
(Reverse Side)

 

 

 

 

INTERESTING SPONGE FACTS

Sponges are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them.

Sponges do not have nervous system, nor digestive or circulatory systems; instead their water flow system perform all the necessary functions.

For defense, sponges shed rod-like spicules forming a dense carpet several meters deep that keep away echinoderms (i.e. starfish) which prey on them. They also may produce toxins that prevent other prey from growing on or near them.

Their bodies have two outer layers, separated by a non-living gel layer which contains the tiny rod-like spicules.

Sponges are sessile (attached to a substrate).

Most sponges live in quiet, clear waters because sediment stirred up by waves or currents would block their pores making it difficult for them to feed and breathe.

Sponges  improve water quality as effective biological filterers, extracting microscopic food and bacteria from the current.

Sponges evolved over 500 million years ago.

Sponges form different shapes, including tubes, fans, cups, cones, blobs, barrels, and crusts.

Sponge Classification

Kingdom Animalia (animals)

Phylum Porifera (having pores)

Classes

Demosponges - Largest class; Inner structure reinforced with collagen fibers and spine-like spicules made of silica minerals; Usually barrel shaped; Can live in a wide variety of habitats; Some are bath sponges

Hexactinellida – Glass Sponges; Spiny spicules made of silica minerals forming inner scaffolding structure with gelatin substance weaved in between framework; likes Polar Regions

Calcareous – Outer exoskeleton and inner spicules made of calcium carbonate. Restricted to shallow marine waters where production of calcium carbonate is easiest to obtain.

Scleropongiae (Coralline or Tropical Reef Sponges) soft body that covers a hard, often massive skeleton made of calcium carbonate, either aragonite or calcite.  The layered skeletons look similar to reef corals, therefore are also called coralline sponges.

Branching and/or Finger Coral

Branching Type Coral Fossil

Branching Type Coral Fossil
(View Large to see minute details)

Branching finger-like corals are a dominant species in the Caribbean, Florida and Bahama ocean reefs and form some of the largest colonies extending as far as eight meters in height. They are very slow growing and therefore some may be a thousand years old.

Club Tip Finger Coral

Club Tip Finger Coral

Because the fossil/skeleton sample in my possession has broken off branches (very typical) I was unable to identify the exact species, but am certain it belongs to the genus called Porites. Three Western Atlantic Porites species have features that overlap so can be difficult to identify.

  • Club Tip Finger Coral (Porites, porites) possess thick, stubby branches growing upright or spread wide apart. Often gray, occasionally bright blue
  • Branching Finger Coral (Porites, furcata) possess elongated, tightly compact branches with rounded tips. Usually grey
  • Thin Finger Coral (Porites, divaricata) possess most slender branches, widely spaced apart, often divided at their tips. Colors vary from purple, yellowish brown, grey and brown.

  

Source: http://foro.fonditos.com/porites-furcata-80-t54240.html

Branching Finger Coral (Close-Up)
Source: http://foro.fonditos.com/porites-furcata-80-t54240.html

CLASSIFICATION

  • Kingdom: Animalia
  • Phylum: Cnardia (stinging cells)
  • Class: Anthozoa (flower animl)
  • Order: Scleractinia (stony coral)
  • Family: Poritidae (massive reef builders)
  • Genus: Porites (finger-like)
Branching Finger Coral Fossil (Opposite Side)

Branching Type Coral Fossil (Opposite Side)
(View Large to see minute details)

Rough Star Coral

Rough Star Coral, Isophyllastrea rigida on the left and Symmetrical Brain Coral, Diploria strigosa on the right. Source: http://www.livingoceansfoundation.org/photo/jamaica-photos/

Rough Star Coral, Isophyllastrea rigida on the left and Symmetrical Brain Coral, Diploria strigosa on the right.
Source: http://www.livingoceansfoundation.org/photo/jamaica-photos/

Rough Star Coral,  Isophyllastrea rigida is commonly found in the Atlantic Ocean along the shores of the Caribbean Islands, Bahamas and Florida. The fossil sample below is part of a collection gathered in the 70′s and 80′s during vacations my husband’s mother and father took from their busy lives. Winkie, my late mother-in-law, faithfully collected sea shells and coral adrift on the beaches, which today is forbidden. Now in my care, it has been my pleasure to research their origins and share them with you on the information highway which she never knew, but would be very proud to share.

Winkie with my late husband Joseph at age three

Winkie with my late husband Joseph at age three

Rough Star Coral (Isophyllastrea rigida)

Rough Star Coral Fossil
(Isophyllastrea rigida)

Rough Star Coral is easily recognized by its small dome-shaped colonies and closely spaced corallites having only a thin margin between them and the polyps are rounded to polygonal in outline. Living colonies of the rough star coral range in color from varying degrees of light green to yellow, usually with the ridges being lighter in color than the darker groove floors.

 

 

It belongs to a family of corals called Mussidae originating during the Cenozic Era beginning 65 million years ago. Mussidae is a relatively small family of coral consisting of roughly 13 genera with a wide geographical distribution. Eight genera from Mussidae are found in the Indo-Malayan Western Pacific seas and the remaining four genera, including the Rough Star Coral, Isophyllastrea rigida are Atlantic species.

Below are living Mussidae corals from the genera of Acanthastrea, a showy and colorful breed with meaty polyps living in the Indo-Pacific regions. The similarities and differences from my Atlantic species, Rough Star Coral, Isophyllastrea, rigada, and Acanthastrea requires a close study to discern.

Acanthastrea lordhowensis

Mussidae (Acanthastrea lordhowensis)
Source: en.wikipedia.org

Acan IMAC QM

Mussidae (Acanthastrea)
Source: http://www.wetwebmedia.com/mussidae.htm

 

Acanthastrea Source: http://www.wetwebmedia.com/mussidae.htm

Mussidae (Acanthastrea)
Source: http://www.wetwebmedia.com/mussidae.htm

CLASSIFICATION: ROUGH STAR CORAL

  • Kingdom: Animalia
  • Phylum: Cnidaria (stinging cells)
  • Class: Anthozoa (flower animal)
  • Subclass: Hexacorallia (polygon shape)
  • Order: Scleratina (stony coral)
  • Family: Mussidae (large fleshy polyps)
  • Genus: Isophyllastrea
  • Species: rigida

 

Coral: A Simple Animal Simply Explained

Corals exist at the tissue level lacking organs, such as a heart. On the evolutionary ladder, corals are one step above the sponges. They are the simplest animals to have a nervous system, and a connected muscular system, and a dedicated reproductive system.

Comparing Two Starlet Corals

 Starlet Coral (Siderastrea, sidereal) Source: httpcoral.aims.gov.aufactsheet.jspspeciesCode=0614

Massive Starlet Coral (Siderastrea, sidereal)
Source:
http://coral.aims.gov.au/factsheet.jsp?speciesCode=0614

Massive Starlet Coral (Siderastrea, sidereal) Fossil

Massive Starlet Coral (Siderastrea, sidereal) Fossil

Massive Starlet Coral (Siderastrea, sidereal) Fossil Underside

Massive Starlet Coral (Siderastrea, sidereal) Fossil Underside

Starlet corals, not to be confused with star corals, are commonly found off the Caribbean, Florida and Bahama shores. I have two species from the genus Siderastrea.  As I’ve mentioned in previous posts, these corals were discovered off Florida’s beaches in the 60′s, 70′s and 80′s by my mother in law Winkie during family vacations.

Massive Starlet Coral (Siderastrea, sidereal ) httpcoral.aims.gov.aufactsheet.jspspeciesCode=0614

Massive Starlet Coral (Siderastrea, sidereal )
Source:
http://coral.aims.gov.au/factsheet.jsp?speciesCode=0614

1983 Winkie Mirto with Son, Joseph  (my late mother-in-law and husband)

1983 Florida Vacation Winkie Mirto with son, Joseph (my late husband)

Siderastrea, sidereal commonly called Massive Starlet Coral is a very slow growing species that lives to a great age forming large colonies sometimes over a meter across. It’s closely related to the commonly named, Lesser Starlet Coral, Siderastrea, radians. You must look very closely in order to observe their differences!

Usually, the way to tell is by distinguishing growth patterns which I’ve provided a comparison chart below. But another interesting way worth mentioning first is by observing the environment where they grow, most people are only able to through pictures. Nevertheless, unlike the Massive Starlet Coral, the Lesser Starlet Coral often looks as though the colony is  growing under the materials around it.

Lesser Starlet Coral (Siderastrea, radians) Source: httpcoral.aims.gov.aufactsheet.jspspeciesCode=0613

Lesser Starlet Coral (Siderastrea, radians)
Source:
http://coral.aims.gov.au/factsheet.jsp?speciesCode=0613

Lesser Starlet Coral (Siderastrea, radians) Fossil

Lesser Starlet Coral (Siderastrea, radians) Fossil

Lesser Starlet Coral (Siderastrea, radians) Fossil Underside

Lesser Starlet Coral (Siderastrea, radians) Fossil Underside

 

CLASSIFICATION

  • Kingdom: Animalia
  • Phylum: Cnidaria (Animals with Stinging Cells)
  • Class: Anthozoa (Flower Animal)
  • Subclass: Hexacorallia (Polygon Structures)
  • Order: Scleractinia (Modern Stony Corals)
  •  Family: Sideractinia
  • Genus: Siderastrea
  • Species: sidereal and radians

COMPARISON CHART 

Massive Starlet Coral (Siderastrea, sidereal)               Lesser Starlet Coral (Siderastrea, radians)

  • Usually Dome Shaped                                                Mostly Encrusting Flat or Uneven Sphere
  • Large Colonies Up To A Meter                              Usually Small Colonies About 1 ft. Across
  • Roundish Corallites (Holes)                                    Somewhat Angular Asymmetrical Corallites
  • Shallow Corallites                                                        Deeper Pitted Corallites
  • Obscure Septa (Ridges)                                             Pronounced Septa (Ridges)
  • Thin Fine Walls Between Septa                             Wider Walls Between Septa
  • Septa Uniformly Separated                                     Septa Separated Unevenly
  • 50 to 60 Septa In Each Corallite                           30 to 40 Septa In Each Corallite
  • Smooth Surface                                                            Pitted Surface
  • Uniform Color                                                              Contrasting Dark Centers
  • Pink, Cream, Brown, Grey                                      Whitish, Grey, Green, Light Brown
  • Depth from 40 to 10 meters                                   Only Shallow Depths 10 meters
  • Not tolerant of tide pools and silt                         Tolerant of tide pools and silt

Maze Coral or Is It Rose Coral

Judging from the title of this article, you may have gathered their can be confusion identifying coral fossils and you would be right. All corals are not single organisms, but rather are a colony of individuals we know as polyps (the jelly like part). The polyps band together and slowly build a calcium carbonate skeleton. Herein lies the physical diversity of corals as each species builds a slightly different style of skeleton.

I feel fairly confident I have several maze coral fossils in my possession inherited from my mother in law, Winkie’s collection. They are commonly found in the Bahamas, Caribbean and Florida shores where she would have discovered them lying on the beaches during family vacations in the 60′s and 70′s.

Can you tell the difference between the maze coral and the rose coral below?

Rose Coral Fossil

Maze Coral Fossil

While searching, I realized that maze corals are sometimes lumped together with brain corals or are even called maze brain corals.  The most distinguishing features from other brain corals is that the maze brain coral have thicker convoluted ridges and well defined plates. Also, there is an indentation running along the crest of the walls where the adjoining plates “corallites” meet. Colonies form both hemispherical heads and or flat plates which fits the description of the one in the photo above.

CLASSIFCATION

  • Kingdom: Animalia
  • Phylum: Cnidaria (Animal with stinging cells)
  • Class: Anthozoa (Flower like animals)
  • Subclass: Hexacorallia (corals having parts in multiples of 6)
  • Order: Scleractinia (Stony Skeleton)
  • Family: Meandrininidae (Meandering Colony Corals)
  • Genus: Meandrina (forms massive hemispherical heads or have large flat plates and can grow to a metre (yard) across)
  • Species: M. meandrites
Rose Coral Fossil (Shows Cone Shape Underside)

Rose Coral Fossil
(Shows Cone Shape Underside)

Rose coral, Manicina, areolata  often have irregular cone shaped undersides and at times consist of a short stalk which can be unattached to the substrate. The most common rose corals form elliptical or oval colonies (shone below) with a long continuous central valley and several short side valleys.

Colors: Yellowish-brown, tan or dark brown, often with the valleys and walls being contrasting colors. Like most corals, the polyps are only extended at night and are often green.

Manicina areolata Rose Coral Fossil

Manicina areolata
Rose Coral Fossil

Manicina areolata Rose Coral Fossil (Underside)

Manicina areolata
Rose Coral Fossil (slight cone shaped underside)

Interesting Behavior

Manicina areolata is one of only a few corals that can be actively mobile depending if its the colony form.

If a small colony gets turned over it gorges its stomach with water to become bloated, and then jets water from one side at a time. This causes a back and forth rocking motion until the center of gravity shifts allowing it to rapidly flip upright. The entire process takes a few hours until the final flip occurs in an instant. Larger colonies are more likely to die by smothering in the sediments placing a limit on the size any given colony can grow.

Second Growth Form (Hemispherical)

Manicina, areolata rose coral occurs in two distinct grow patterns making matters even more confusing. The second form consists of semicircular heads with  flattish undersides, winding wide valleys and ridges forming irregular furrows. 

Manicina aerolata Source: http://reefguide.org/carib/rosecoral.html

Rose Coral Manicina aerolata
Source: http://reefguide.org/carib/rosecoral.html

Rose Coral Fossil

Rose Coral Fossil

Habitat: Rose coral Manicina, aerolata is very abundant off the Floridian shores as well as the Bahamas and Caribbean. It prefers shallow, productive near shore habitats characterized by abundant sediments such as seagrass meadows, or along the fringes of mangrove forests.

CLASSIFICATION

  • Kingdom: Animalia
  • Phylum: Cnidaria (Animals with stinging cells)
  • Class: Anthozoa (Flower Animal)
  • Order: Scleractinia (Stony Skeleton)
  • Family: Faviidae (generally spherical shape and grooved surface which resembles a brain)
  • Genus: Manicina
  • Species: M. areolata

The genus Manicina sp. includes over 10 species, but Manicina areolata is the only species that survives today. The heyday for Manicina was during the Miocene and Pliocene eras between (24 million to 1.6 million years ago). About one million years ago, approximately half the species of reef corals living in the Caribbean became extinct.

Low Relief Lettuce Coral

Low Relief Lettuce Coral Fossil (Agaricia, humilis)

Low Relief Lettuce Coral Fossil (Agaricia, humilis)

Low relief lettuce coral is common in the open seas of the Caribbean, Bahamas and Florida often scattered among other corals and in inner bays sometimes on mangrove roots. It can thrive from shallow sea-levels to the lower depth limits of the reef, approximately 60 meters deep. This species, in its widespread distribution, shows a number of growth forms, which sometimes are considered varieties or even species.  They can appear saucer like on cliff sides or in shallow depths, small and half moon shaped. In depths deeper than 10 meters the coral forms broad vertical scales with corallites on one side only.

CLASSIFICATION:

  • Kingdom: Animalia
  • Phylum: Cnidardia (C is silent) Marine group with stinging cells
  • Class: Anthozoa – Flower Animal
  • Order: Scleratinia – Reef building stony corals
  • Family: Agariciidae - includes cactus coralselephant skin coralsplate corals and lettuce corals. Members of the family include symbiotic algae called Zooxanthellae in their tissues which help provide their energy
  • Genus: Agaricia – lettuce corals
  • Species: humilis – low relief
Winkie, Joe, Johnny and Joey

Winkie, Joe, Johnny and Joey

 

 My mother in law Winifred (Winkie) loved collecting coral during Florida vacations in the 60′s and 70′s.  My late husband, Joseph, came from a hard working family in the 50′s living in Detroit. His dad, Joseph, was a designer for Chrysler Corporation and designed an amphibious vehicle used in WWII.    

I am honored to have her coral collection and look forward to sharing more of it in the near future.