Spiny ammonite (Cioceras nolani) fossil. Fossilised remains of a rare spiny ammonite in its host rock. Ammonites are shelled cephalopods that lived from around 400 to 65 million years ago, becoming extinct at the end of the Cretaceous period. This specimen dates to around 120 million years ago, from the Hauterivian stage of the Cretaceous period, and has been released from its host rock (gangue) very carefully to keep its spines intact. This specimen was found in Provence, France and has a diameter of 45 cm.