A single fossilized shell 1.5 x.375 inch diameter
Belemnites are extinct squid-like cephalopod mollusks, close cousins to ammonites, that lived throughout the Mesozoic era, 250-66 million years ago. Unlike the ammonites, the belemnites had straight shells instead, making them look more modern squid-like than the ammonites. Superficially squid-like, they had ten arms of equal length studded with small inward-curving hooks used for grasping prey. Belemnites also had hard internal skeletons. In both belemnites and squid, the molluscan shell is internal, though in modern squid it is reduced to a simple, chitinous ‘pen’. In contrast, the belemnite shell was complex.