Small Category for the bullet like creatures that were also related to squids and ammonites, and very much like today's cuttlefishes. Belemnites first appeared in the Triassic era. They went extinct in the late Cretaceous. Belemnites were superficially squid-like. They possessed ten arms of equal length studded with small inward-curving hooks used for grasping prey. However, they lacked the pair of specialized tentacles present in modern squid.
Belemnites (and other belemnoids) were distinct from modern squid by possessing hard internal skeletons. The internal skeleton was composed of the guard or rostrum, a heavy solid structure at the posterior of the animals. The rostrum was usually bullet-shaped and projects prominently backward, but in the suborder Belemnotheutina, it was only present as a thin layer. Due to its more geologically stable calcite constitution, the rostrum is often the only remains of the animals preserved, often in very large numbers.