Two Genus’s of Brain Coral


Colpophyllia, natans
(Boulder Brain Coral Fossil)


Colpophyllia, natans (Boulder Brain Coral) Source:

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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:

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.



11 thoughts on “Two Genus’s of Brain Coral

    • Coral are one of the most diverse and difficult species to identify. I often can get down to the genus and am unable to narrow down to species, especially when judging by fossil remains. Give it a go and best of luck!

    • Thanks for stopping by Sally, yes indeed, coral is an indication of ecological change for us to pay attention to the disturbances we’re causing. Take Care, Kathi

  1. We are in saugatuck area and have a small creek by U.S. We have found hundreds of nearly all these fossils since we moved in. I’ve collected a handful in my lifetime but can collect that in a hour now. Thanks for all your helpful photos and information!

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