Finding out more

Ammonites are tiny shelled creatures that scientists say lived in the oceans, billions of years ago. Considering that no one has ever seen one alive, we think we know a lot about them.

Why do scientists think ammonites once lived in our oceans? Ammonites were plentiful, say scientists, and we know this because their fossils can be found in many places. Although ammonites are sea-creatures, the sites where the fossils are found are no longer seas. We now find them in rocks!
But how does an ammonite become fossilised?