Belemnites are prehistoric squid-like cephalopods that flourished in Mesozoic seas.
Like squidsbelemnites possessed an ink sac and ten arms. Belmnites were among the earlier members of this group, and probably ancestral to modern forms. In appearance and habits, a live belemnite would have greatly resembled a modern squid. But it differed in that it had a more developed internal shell. The solid conical rostrum, is the strongest part of the shells are often preserved as fossils.