4.5" Jurassic Belemnites (Youngibelus) - Posidonia Shale, Germany

This is a fossil belemnite (Youngibelus gigas) from the Posidonia Shale in Germany. It's been left partially embedded in the rock it was found in.

Belemnites are probably the most well known extinct cephalopod after the ammonites. They lived during the Jurassic and Cretaceous periods and are fairly common fossils found throughout the world. They had a hard, internal, cone shaped structure that is often preserved as a fossil though it is not technically a shell. They had 10 arms but unlike modern squid these arms had small hooks instead of suckers.