Ostrea edulis

A very small damaged oyster specimen. Fossil oyster shells can be frustratingly difficult to tell apart from modern specimens.  

Different oyster species can be very hard to recognize, but O. edulis is by far the most common, so it's usually a reasonably safe bet (the other species are rare Pliocene to Eocene species and are very rarely found). 

Note: this particular specimen is pretty cool, because it's a great example of bioimmuration. Can you see those weird lines on that shell on the left hand side? That's the imprint of another shell species (bivalve or gastropod) which the oyster grew attached to. 

Status: still locally alive

Fossil occurrence: common