Polished Goniatite

A goniatite is a fossil of an extinct marine animal that lived hundreds of millions of years ago. It belonged to a group called ammonoids, which are relatives of modern creatures like the nautilus, squid, and octopus.
These animals had coiled shells—kind of like a ram’s horn—and lived in ancient oceans from about 400 to 250 million years ago, during periods like the Devonian Period and Permian Period.