My first impression is that you have a species of Cerastoderma, probably glaucum (Bruguiere, 1789) , or a species close to C.eichwaldii (Reeve, 1845)

Dear Jorgen thank you very much for your answer. To which period would this genus and/or species belong? What does imply finding of this fossil

in Kosovo? Many thanks.

First check out where this specimen was found, with this publication and website you might have a clue regarding the period :

http://olteniastudii.3x.ro/cont/25/P04-Elezaj.pdf

http://www.kosovo-mining.org/kosovoweb/en/mining/geology.html

It's a Cardiidae, but a determination on species-level is doubtfull with an endocast...

Sorry, but I am not a paleontologist. I have some experience with extant cardiids and I found that your shell looked like a cardiid. I hope somebody else can have a more precise opinion.

As much as I can see (shape, sculpture) it Is a member of the family Cardiidae. Do you have any Information about the geological formation (aprox. age) where you found it?

Regards

Juan

Thank you all for answers