Tridonta borealis

A very nice boreal astarte shell. 

The age of these shells is unsure. Although it is often found in Eemian localities (ie Banjaard, Zandmotor, etc), the water was probably too warm for this species during the Eemian interglacial period, so it probably isn't from that period. Some scientists estimate this shell's age as a bit younger, perhaps from the Weichselian, about 80'000 years old. 

Note: the shells of this species from the Banjaard are often found with the periostracum ("skin") still slightly preserved on them, a structure that normally always disappears during fossilization! If you zoom into the lunula on the right hand side, you can kinda see a black spot there. That's the periostracum! Doesn't sound like much, but it's a fun and uncommon phenomenon.  

Status: locally extinct

Fossil occurrence: rather common

WoRMS synonym: Astarte borealis (Schumacher, 1817)