Hello,

I think it is a fragment of Ostra (recognized in the Ain Grab formation, Miocene)!!??

Hello Kamel,

Thank you for your answer, but I don't think so because this fossil has large vertical costulations while Ostrea has remarkable growth lines perpendicular to the hook.

Karoui-Yaakoub:

Would you be kind enough to photograph the specimen/s in different views and test the mineralogical composition. This would really help.

Best

Syed

It would also be helpful to know from what kind depositional environment it comes from.

It would also be helpful to know from what kind depositional environment it comes from.

 It is collected from marine sediments : Paleocene-Eocene interval.

Dr. Abbes;

It is the only specimen collected and is photographed on its two faces.

The short answer: I don't know. The pictures are fuzzy and not sufficient to decide, and the lack of depositional and paleoenvironmental information does not help.

A slightly more helpful answer: it might be a solitary scleractinian theca partly crushed and fragmented, so the septa near the top of the theca are not in their original radial orientation and therefore not easily identifiable. It might even be a fragmentary reworked rudist from Mesozoic layers. Even less likely since I see no sutures on the external surface, it might be a crushed barnacle capitulum. Without seeing pictures from the sides that might show a commissure line (or its absence), I would not exclude a fragmentary oyster, either. And the list of possibilities is not even complete.

Just spitballing here, but if it was a Cenomanian sequence, I would identify this specimen as a radiolittid rudist bivalve.

Yes, this seems a fragmentary shell of oyster.

 Thank you all my colleagues,

I cheked the microfauna, I determinated the Maastrichtian planktonic foraminifera such as G. Gansserina and Globotruncana species, so I think that this fossil is a rudist bivalve.

dear Karoui-Yaakoub Narjess

 I think it is a rudist shell.

Best,

Riccardo

 Thank you Dr. Ricardo, I become more convinced now.

Thank all colleagues for your help.

Best