Ammonite
How to recognise them
Spiral shell, narrow whorls.
Fossil Info
Ammonites are a type of cephalopod animal related to modern-day squid and octopus that lived from the Devonian Period around 400 million years ago but went extinct during the end-Cretaceous mass extinction event. They had large eyes for finding prey and many were built for speed, with hydrodynamic shells with tapered edges. Their shells have beautiful patterns made by the very complex sutures or joins between the body chambers in the shell. During growth, these animals compensated for the heavier shell by allowing gas to diffuse into the central body chambers through a tube called the siphuncle.
Fun Fact
Ammonites were once thought to be curled-up sea snakes!
Find out more about Irish Ammonites on the National Museums NI website