A model of an Ammonite fossil removed from the surrounding stony matrix. The fossil is a museum specimen, about 60 cm in diameter.

Ammonites were a group of now extinct cephalopods. Their closest living relatives are the octopuses, squids and cuttlefish. There were many different species ranging in size up to about 2 metres in diameter. As a group they finally became extinct at the same time as the dinosaurs about 65 million years ago.