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 in inner bays and 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 has a widespread distribution. It shows a number of growth forms. It can appear saucer like on cliff sides or small half moon shaped in shallow depths. In depths deeper than 10 meters, the coral forms broad vertical scales with corallites on one side only.


  • 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 feel honored to have samples from her coral collection and am excited to share it with you. She would have been thrilled by this.  


Cactus Coral Pavona

Cactus Coral Pavona

Cactus Coral Pavona Fossil

After much digging around I believe I have properly identified this as a cactus coral from the genus of Pavona.

Note:  The small prickly pattern of polyps were the best defining feature as well as the folding plates that resemble a cactus.

The Pavona Coral is a small polyp stony coral, and can be referred to as the Cactus, Potato Chip, or Lettuce Coral.  A single species may vary in form according to the current, wave action, lighting conditions and depth of its location. They can also vary in color from shades of light and dark brown to green with cream or white margins. Some have a fluorescent glow that can be seen beneath the polyps, giving these corals an interesting look. They are known to make a popular addition to the home aquarium.


Closely spaced polyps of Cactus Coral Pavona Fossil

Closely spaced polyps of Cactus Coral Pavona Fossil

Cactus Coral Pavona Source: "Douglas Illistration":http://www.freewebs.com/douglasillustration/reeftank.htm

Cactus Coral Pavona
Source: “Douglas Illistration”:http://www.freewebs.com/douglasillustration/reeftank.htm


  • Kingdom: Animalia
  • Phylum: Cnidardia is a group containing over 10,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey.
  • Class: Anthozoa (flower animal)
  • Order: Scleratinia also called stony corals, are marine corals that generate a hard skeleton. They first appeared in the Middle Triassic and descended from the tabulate and rugose corals that barely survived the end of the Permian. Much of the framework of today’s coral reefs is formed by scleractinians. Stony corals numbers are expected to decline due to the effects of global warning and increased acidity due to pollution.
  • Family: Agariciidae reef building stony corals including  cactus corals, elephant skin corals, plate corals and lettuce corals
  • Genus: Pavona coral colonies of this species have vertical, irregular, two-sided fronds
  • Species: likely minuta or duerdeni

A soothing 30 minute video set to music vividly depicting coral habitast. See if you recognize some of the species I have introduced from my collection.


Two Related Genus’s of Star Coral

Elliptical Star Coral

Elliptical Star Coral Fossil (Click to view large for fine details, then arrow back)









Because the variety of corals is so vast, it can be difficult  to identify species which requires a discreet eye. After close examination and research, I believe I have targeted its identity!

Elliptical star coral is named for its oval elongated shaped corallites or the calcareous cups from which the polyps protrude. Scientifically named Dichocoenia, stokesi, shown above, is a massive colonial coral that forms round humps up to 16 inch (40 centimetres) in diameter. These two characteristics coincide with my fossil quite well.

It is a fairly uncommon species, and has been placed on the Red List for Endangered Species. In 1995 off the Florida Keys, Dichocoenia, stokesi suffered from a disease called white plague which killed 95% of its colonies. It’s a slow growing variety for which the struggle to come back is fast diminishing, unless we humans do something about its plight and that of many other coral varieties.

Kingdoms : Animalia

Phylum:  Cnardia (Marine group with stinging cells)

Class:  Anthozoa (Flower Animal)

Order:  Scleratinia  (Modern species of Stony Coral)

Family:  Meandrinidae (meandering  form)

Genus: Dichocoenia (hump-forming or flattened corals with irregular calyces)

Species: stokesi (elliptical or pineapple star coral)

Blushing Star Coral Fossil

Blushing Star Coral Fossil (View Large)

Blushing Star Coral Fossil Side view showing flat plate form)

Blushing Star Coral Fossil
(Side view showing flat plate form)






Stephanocoenia, intersept  have tentacles that are commonly extended during daylight, unlike most coral. When touched, it rapidly retracts them causing a slight color change, which gives this coral its common name of “Blushing Star Coral”. It can be found in Florida, the Caribbean and Central American regions and as far south as Brazil. It’s found in a number of reef habitats including channels and lagoons. It grows massive encrusting colonies forming flattened domes. Corallites can be circular to polygonal. The two characteristics of flattened domes and corallite shapes are in line with my coral fossil shown above.

Nutrition: Like all coral, it has a symbiotic relationship with algae zooxanthellae. Through photosynthesis, the algae provides energy to the coral which in turn homes the algae. Food is caught as it passes by the coral tentacles whereby stinging cells called nematocysts stun and hold onto it.

Its earliest fossil record dates back to the Eocene period between 55 and 33 million years ago.

The Blushing Star Coral is also susceptible to white plague type II which exposes the skeleton by rapid tissue destruction and is also on the Red List of Threatened species.

star coral blushing 3

Blushing Star Cora. (View Large)

Kingdoms : Animalia

Phylum:  Cnardia (Marine group with stinging cells)

Class:  Anthozoa (Flower Animal)

Order: Scleratinia (Modern species of Stony Coral)

Family:  Astrocoeniid  (small family made up of  both reef building and non reef building  genus, both with and without symbiotic zooxanthellae as well as both branching and encrusting species.

Genus: Stephanocoenia (Colonies are flattened usually with regular, smooth surfaces. Corallites are small and the wall between them may be relatively wide.)

Species: intersepta


Comparing Two Star Coral Species

From the Upper Jurassic to recent times The Great Star Coral, Montastrea cavernosa, forms sizable massive heads and sometimes plate-like structures. The polyps can be quite variable in color, from green and brown to bright red.  It’s a dominant species at moderate depths off Palm Beach County, Florida and the windward shore of  Barbados.  It can also occur in the Caribbean, the Bahamas, the banks off the Texas coast, Bermuda, Brazil and off western Africa.  It’s one of the deepest occurring corals found at depths from only a few meters to at least 90 meters.

Montastrea cavernosafossil

Montastrea cavernosa (The Great Star Coral) fossil


Monstastrea cavernosa (star coral) fossil side view

The fossil above is another in my possession from my late mother-in-law Winkie (Winifred) Mirto. She gathered a small collection off the Florida coast before protection laws forbid people to do so.

1983 Ft. Lauderdale Florida Winky and Joe

1983 Ft. Lauderdale Florida
Winkie and Joe

Threats to Montastraea cavernosa include coral bleaching, ocean acidification and coral disease, especially black band disease and white plague.

Choose Your Sunscreen Carefully

Montastraea are hermatypic, containing symbiotic algae called zooxanthellae that help nourish it, provides it oxygen and dispatch waste.

Montastraea, cavernosa with open tentacles source: commons.wikipedia.org

Montastraea, cavernosa with open tentacles
source: commons.wikipedia.org


Kingdoms : Animalia

Phylum:  Cnardia (Marine group with stinging cells

Class:  Anthozoa (Flower Animal)

Order:  Scleratinia: (Modern species of Stony Coral)

Family:  Faviidae (Generally spherical shaped grooved surfaces)

Genus:  Montastraea

Species:  cavernosa (above) annularis (below)

Montasrea annularis

Montastrea annularis (Boulder Star Coral) fossil

Montastaea annularis commonly known as the Boulder Star Coral, co-occurs in near abundance with M. cavernosa only it dominates in the Caribbean regions. It also grows in varying depths down to 80 meters and grows in varying colony shapes (heads, column, or plates) in response to differing light conditions.


Montastraea annularis
Source: en.wikipedia.org

Competition between the cousin genera has shown them to adapt longer sweeper tentacles in order to attack intruding corals.


Montastrea cavernosa Source: commons.wikipedia.org

Montastrea cavernosa
Source: commons.wikipedia.org


Winkie’s Pillar Coral Fossil

Pillar Coral (Dendrogyra, cylindricus)  Source: en.wikipedia.org

Pillar Coral (Dendrogyra, cylindricus)
Source: en.wikipedia.org

Pillar Coral is one of the most spectacular stony corals found in the western Atlantic Ocean and Caribbean Sea.  It derives its name for obvious reasons with its finger like branches. They can reach a height of nearly 3 meters.

Pillar Coral Fossil (Dendrogyra, cylindricus)

Pillar Coral Fossil (Dendrogyra, cylindricus)

This pillar coral fossil is another sample given to me by my late mother-in-law, Winifred (Winkie). She gathered her coral fossil collection along Florida coasts during an era when it was okay to do so.  Colonies were once more common along the Florida reef, but commercial collections has greatly reduced its occurrence. Otherwise, pillar coral (Dendrogyra, cylindricus) is found commonly along coasts of Jamaica and Bahamas.

Dendrogyra, cylindricus is unusual in that the polyps with their tentacles are expanded in the daytime unlike most other stony coral.  The tentacles sway with the current and if one portion of the colony is disturbed by touching so that the polyps contract, a wave of contractions of the other polyps can be seen to pass over the entire colony in a period of a few seconds.     

Pillar Coral (link to clear photo)


Kingdom: Animalia

Phylum: Cnidardia (large marine group characterized with stinging cells, tentacles and no skeletons or organs)

Class: Anthozoa (Flower Animal)

Order: Scleratinia (Stony Coral)

Suborder: Faviidae (General Spherical Shape)

Family: Meandrinidae (Meandering valleys between corallites)

Genus: Dendrogyra

Species: Cylindricus

What’s being done to bring back the threat of coral? Coral farming, see video to find out about this effort to restore the reef along Florida Keys.


Hope you enjoyed this display of pillar corals and learned some things along the way.  I feel privileged to have inherited this sample as part of a collection from my beautiful mother-in-law Winkie.

1983 Ft. Lauderdale Florida Winky and Joe

1983 Ft. Lauderdale Florida
Winkie and Joe

Winifred (Winkie)

Winifred (Winkie)

Two Genus’s of Brain Coral


Colpophyllia, natans
(Boulder Brain Coral Fossil)


Colpophyllia, natans (Boulder Brain Coral) Source: en.wikipedia.org

Click on the images to enlarge for fine details, then arrow back

The coral genus groups Diploria and Colpophyllia both belong to the family of Faviidae and earn the common term “brain coral” due to their convoluted surfaces and general spherical shapes.  They are slow growing, colony forms which may reach colossal sizes a few meters in length and live for 100’s of years. The oldest know brain coral is 900 years old. Both these species grow in shallow parts of the Caribbean Sea, the Bahamas, Bermuda and Texas, as well as Florida.


Symmetrical Brain Coral Fossil
(Diploria, strigosa)

Symmetrical Brain Coral (Diploria, strigosa) Source: http://reefguide.org/carib/pixhtml/symmetricalbrain2.html

Symmetrical Brain Coral
(Diploria, strigosa)



Colpophyllia, natans  or Boulder Brain Coral is a very large brain coral whose domed hemispherical colonies may exceed one meter across. Smaller colonies may be flat topped discs. Its valleys may stretch the entire width, or be subdivided into shorter series. The valleys and walls may be two centimeters broad distinguishing it from the genus group, Diplorias sp., which are narrower. Walls commonly have a fine groove running along their tops. There is a sharp break between the wall and the valley floor. The colors vary with ridges being various shades of brown, and the valleys either whitish, green, or tan.

Diploria, strigosa, or Symmetrical Brain Coral forms  flat plates or massive hemispherical domes up to 1.8 meters, 6ft. diameters. There are sometimes and sometimes not a very narrow groove along the tops of the walls, and the walls have sloping or rounded sides. Valleys may run straight for considerable distances or be highly irregular in direction. They range in color from purplish brown to grey or green, often with the groove floors being a contrasting paler color.


  • Kingdom  –  Animalia
  • Phylum  –    Cnidaria (means stinging cells)
  • Class  –     Anthozoa (means flower animal)
  • Order  –  Scleratinia (stony skeleton)
  • Family  –  Faviidae (spherical group with grooved surfaces)
  • Genus  –  Diploria /  Colpophyllia
  • Species – strigosa /  natans

Diploria, strigosa is the most widespread of all the Diploria species, being more resistant to threats with the ability to thrive in muddy stretches of seabed where  many other corals are not able to flourish.

Brain Coral Open Polyps At Night

Brain Coral Open Polyps At Night

ABOUT SCLERACTINIA: The order, Scleractinia, in which all living corals belong today, means they develop a stony skeleton. They possess a light, porous skeleton consisting of external sheathing which forms a cup. Scleractinians were fairly rare in North America until the Cretaceous, about 100 million years ago, when they first built reefs in Texas and Mexico. It wasn’t until the Pleistocene Period, about 2.6 mya, that reefs flourished where they do today.

NIGHT TIME ACTIVITY : The coral polyps, the living breathing jelly-like part of the animal, are found in single file in the valleys of the convolutions. They are normally contracted during daylight, but expand at night to catch microbits of food drifting by.


Fossillized Algae


Did you know algae are the oldest fossils found on Earth that can be seen with the naked eye?

I may be guessing, but I believe I picked up a fossil sample of algae from Lake Michigan’s Oval Beach in Southwestern Michigan (USA) shown below. Algae come in a variety of shapes and forms. They range from single cell organisms such as microscopic phytoplankton to multicellular, such as in the case of giant kelp that can grow as tall as 65 meters.




Algae fossil found on Oval Beach, Saugauck, MI, USA

So why is algae important to you and me?

The answer is:  Algae are the most important photosynthesizing organisms on Earth! A byproduct of photosynthesis is oxygen. Algae produces more oxygen from the Sun’s energy than all other plants combined.

They also form a beneficial partnership with other organisms such as with reef building coral which over time constructs limestone.

Fossilized algae has dated as far back as 1.7 billion years ago.

Flip side of algae fossil with unidentified patterns

Flip side of algae fossil with unidentified patterns

I have a sample of Petrified Algae from which I purchased years ago which has been tumbled and polished smooth. This algae once flourished in warm seas over what is now Minnesota, USA. It is estimated to have lived some two billion years ago. The algae has been petrified or replaced with jasper. The redish pattern in the stone is where the algae used to be. Jasper is a type of quartz that is dense, finely grained, with up to 20% foreign materials that determines its color.

Petrified Algae replaced with Jasper

Petrified Algae replaced with Jasper