Ammonite

Ammonites were a group of marine molluscs related to modern octopus, squids and cuttlefish that first appeared in the Devonian Period (about 400 million years ago) and went extinct 66 million years ago at the end of the Cretaceous Period. Unlike octopus and squids and cuttlefish, ammonites have a large external shell that makes them look a bit like huge snails.