Ammonite

Ammonites were a group of marine cephalopod molluscs with flattened, streamlined, discus-shaped shells, which lived in the open water of ancient seas from the Devonian to the Cretaceous.

Real life
Ammonites were a group of marine cephalopods, which first appeared 400 million years ago and died out in the K-T mass extinction event 65 million years ago. They were known for their shells' spiral shape and loose resemblance to a closed ram horn.