Rugosa horn coral?

[terrain_inconnu]

I found this at a beach on Ikaria island in Greece (Ikaria upper unit, so called Fanari nappe) and it was suggested that this contains horn coral. If this is indeed the case, that would be at least late Permian (i.e. 250 million years ago). The area hosts ophiolitic molasses (conglomerates and olistostromes) that have not experienced high pressure metamorphism but I don't think they are this old. While I like the specimen in its own right, I am more interested in how it fits the geological context of the area.

 

[Mark Kmiecik]

I would say yes, but I'm not 100% certain, so wait for a few other people to see it.

[Rockwood]

The semicircular shape looks like a horn coral. If none of the surrounding outcrops match this rocks appearance there is a good chance glaciers have transported it there. That's going to make a precise age hard to determine. Someone may be able to narrow the possibilities a bit though. 

[TqB]

With only that much of it to see, it could well be a piece of a scleractinian, so from Triassic to Recent. ("Horn coral" can apply equally to the shape of many rugose and scleractinian corals so isn't a very useful term.)

[Rockwood]

Dang, we're losing ground.   

[terrain_inconnu]

I am adding a few more shots from the rock, maybe someone can identify additional fossils that might narrow down the age of the specimen.

 

 

 

 

 

[terrain_inconnu]

13 hours ago, TqB said:

With only that much of it to see, it could well be a piece of a scleractinian, so from Triassic to Recent. ("Horn coral" can apply equally to the shape of many rugose and scleractinian corals so isn't a very useful term.)

Based on the pattern of the septa, scleractinian seems to be the right hint and certainly better fits the age of the geological unit the rock was found (Oligocene to Early Miocene). Quoting from the Digital Atlas of Ancient Life (source):

 

Like Paleozoic rugose corals (and some tabulate corals), the skeletons of scleractinian corals have radial structures called septa. In scleractinian corals, these are arranged in multiples of six. Six or 12 primary septa are deposited first. Secondary septa are then inserted between the primary septa, and this is followed again by later insertion of tertiary (3rd order) and quaternary (4th order) septa. This is illustrated below in the modern coral Flabellum.

 

 

In the specimen under examination a similar pattern for the septa is clearly visible (up to 3rd order):