Ammonites

Ammonites are mollusks that lived in the sea at the end of the Cretaceous period, about 145 to 66 million years ago. They have a spiral-shaped shell and belong to the family of squid. They also had fine tentacles. Youw can find them in petrified state, among other chalky stone layers as on the coast of Cap Blanc-Nez.
Some ammonites were gigantic. The largest ammonite ever found has a diameter of 2.5 meters, these are very rare.