Goniatites

Goniatites are a type of ammonoid, a group of extinct marine mollusks that thrived in the world’s oceans from the Devonian period (around 400 million years ago) through to the Permian period (ending about 250 million years ago). Known for their characteristic spiral shells, goniatites’ shells were segmented into chambers, which they used for buoyancy. As they grew, they moved into new chambers, leaving behind smaller, air-filled segments that helped them float through ancient seas.