Ammonites
Many years ago people who found ammonites did not know they were real fossils, and thought they were snakes that had been magically turned to stone.
Today we recognise them as an extinct group of cephalopods and their coiled shells will be familiar to any fossil hunter.
Because ammonites are extinct, and only their shells are fossilised we do not know exactly what the animal looked like. However, because they are quite closely related, we can use Nautilus to guess what they were like, and how they lived. Like nautiloids, ammonites were marine, they probably floated passively in the oceans eating tiny shrimp and other small animals.
Ammonites were a diverse group found throughout the world.
They were most common in the Jurassic and Cretaceous periods, but died out at the same time as the dinosaurs, 65 million years ago, at the end of the Cretaceous.
On the right, a Jurassic ammonite cut and polished to show its inner structure.
Ammonites come in many different shapes and sizes.
