Most people are familiar with ammonites (see Fossils Explained 62, this issue), with their beautiful, logarithmically spiralled shells, but not everyone has heard of goniatites. They too were fascinating dwellers of past oceans. Goniatites are extinct cephalopods ranging from the middle of the Devonian to the end of the Permian. Although, in the strictest definition, goniatites are those ammonoids that belong to the order Goniatitida, the term goniatite is commonly used as a synonym for all Palaeozoic ammonoids. In the course of this article, the looser definition will apply.