Orthoceres was one of the first members of the class Cephalopoda to appear in the fossil record. Cephalopods are fast moving predatory marine invertebrates. Orthoceres occupied an elongated straight cone shaped shell. This extinct group of ‘uncurled’ cephalopods first appeared during the Ordovician Period. Morocco has vast deposits of Devonian Limestone which date back three hundred fifty million years. As the shells of the creatures accumulated on the sea floor, they were buried by sediments and, over the ages, transformed into stone by physical and chemical processes.