They were formed through a geological process known as opalization, wherein organic material from ancient ammonite shells is ...

Ammonite shells are used today as index fossils, meaning they can help date other fossils that are found in the same layer of marine rock. These cephalopods make for ideal index fossils because ...

Fossilised ammonite shells can be found all around the world, including on parts of Britain's coastline. But if you can't get to a beach to find some, why not start your own collection from home?

An ammonite fossil with a carved snake's head Zoë Hughes, Curator of Fossil Invertebrates at the Museum, explains, 'Ammonites are extinct shelled cephalopods. All of them had a chambered shell that ...