What type of coral fossil?

[Kribensis]

I recently acquired a large collection of fossils at an estate auction in Florida. About half were identified but the rest weren’t.  Most identified fossils were labeled with a location in Florida but not all. 
 

I think this is a fossil of brain coral but the cylinder shape and knob at one end have me me perplexed.  Can anyone help?

Edited October 19, 2022 by Kribensis

[FranzBernhard]

Welcome to TFF from Austria!

Yes, I think brain coral, too. But I don´t think its a fossil. It seems to have grown around something, hence the cylinder shape. Same for the knob.

Franz Bernhard

[Kribensis]

I’m not sure if it’s a fossil or not.  I live in Palm Beach County, which is just north of Miami and we don’t have a coral reef but 100s of millions of years ago we did.  “Fossil” coral washes up on the beach from time to time like the picture below but I’m not sure how to tell the difference between a fossil and just a piece of old coral.  The ones that look like the picture below seem to get classified as fossils.   I wonder if there is an easy way to tell whether a piece you find on the beach is a fossil or not?  
 

 

[FranzBernhard]

37 minutes ago, Kribensis said:

I wonder if there is an easy way to tell whether a piece you find on the beach is a fossil or not?

This is beyond my knowledge, but I will tag one local expert: @digit. Thank you!

Franz Bernhard

[Mahnmut]

Hi Kribensis and welcome to the forum!

thats a very cool shape, probably grew around something long and thin.

It resembles pliocene Manicina  ("Rose-")corals, not sure about older or younger relatives.

Best Regards,

J

 

[Kribensis]

Thank you!  A quick search of the internet finds  Manicina fossils are found in Florida and do look like it.  Also, since it came out of a fossil collection that is mainly Florida fossils, makes sense that it is (a) a fossil and (b) from Florida.

Edited October 19, 2022 by Kribensis

[digit]

This looks too modern to be fossilized and it is more likely to be a recent coral skeleton. The shape is suggestive of the Pillar Coral (Dendrogyra cylindrus) but the polyp structure is wrong for that species. It is a meandroid (brain) coral most likely in the genus Pseudodiploria and more likely P. strigosa than P. clivosa.

 

https://www.google.com/search?q=pseudodiploria+strigosa+skeleton&tbm=isch

 

 

Cheers.

 

-Ken

[Mahnmut]

Hi Ken,

I do not mean to contradict, the only thing I could recognize was a resemblance to Manicina which I know only because I have one in my collection.

I Just wonder what tells you it is modern, as pliocene fossils from florida seem to be often in perfect condition, to my eye indistinguishable from modern ones. 

Could you elaborate?

Best Regards,

J

[digit]

Discussing differences of opinion is how we attempt to resolve questions of fossil ID (and science in general).

 

Modern corals in the genera Colphophyllia, Manicinia, Diploria, Pseudodiploria, Meandrina, Dendrogyra, Mycetophyllia and Isophyllia are all meandroid "brain corals" from the tropical western Atlantic. The modern corals in the genus Manicinia are noted for having a groove in the ridge tops between the polyps. This is not shown in the coral in question here and would exclude modern Manicinia.

 

I know my modern TWA species of corals pretty well having done coral reef research for the past couple of decades and generated lots of training materials to help surveyors identify corals (and fishes and invertebrates). I can easily recognize my modern corals when living but it is more difficult to discern the species from skeletons and I'm of no use at all in extinct coral species as that is outside my wheelhouse for the survey work we did.

 

I've seem a fair bit of fossilized corals in places like the Keys where you can see them (in cross section mostly) where limestone blocks were quarried. Older fossilized corals tend to have more beat-up septa (thin plates around the coral polyp) and more limestone infilling if the coral had been buried. This specimen (to my eyes anyway) looks to clean and appears to be a coral head that might have been tossed up onto the shore by some storm. I remember seeing similar modern coral skeletons on the storm-washed shores of several islands I've visited in the Caribbean.

 

Cheers.

 

-Ken

 

   

[Josesaurus rex]

I have two fossil corals from the Dominican Republic and I also have a modern coral skeleton from Isla de Pascua (Rapa Nui), which I inherited from my grandfather.

 

Based on my experience, I have noticed that if you carefully tap your finger, specifically the nail, you can distinguish different sounds. 

Modern coral would sound more like when you hit a glass or piece of pottery, instead fossils, sound more like stone, it is a little audible sound. 

 

I couldn't say what species your piece is, but I hope my comment will help you at least distinguish whether it's a fossil or not. 

[Kribensis]

Based on the fingernail test it’s a fossil. 
 

Thanks to all for your help. 

[Kribensis]

Turns out the original owner of this fossil has posted and described it on this site.  
 

He stated it was a fossil of a Diplorial Clivosa (brain fossil) growing around a Gorgonian Whip. The Gorgonian Whip is at the bottom and you can see it in the middle of the picture of the bottom. 
 

Thank you all again. 

[digit]

Ah, nice to have an additional insight on this piece. I agree that this coral does seem to have been growing around a cylindrical substrate and a gorgonian could well explain the hollow central core. The polyp pattern looks a bit more like Pseudodiploria strigosa than Pseudodiploria clivosa to me which has less regular and sinuous ridges. I'd have to study it more to be more definitive. for the record, both of these species have been split away from the genus Diploria into the new genus Pseudodiploria leaving only Diploria labyrithinifolia as the sole specimen in this genus.

 

 

Cheers.

 

-Ken