Abberant Ammonite Fossil, Ancyloceras matheranianum, Lower Cretaceous, Russia
Ammonites are the common name given to the Ammonoidea, an extinct order of cephalopods. These relatives of today's squid, octopi, and Nautilus were abundant, intelligent, active, and predatory molluscs that lived in shallow (100 meters or less) marine environments throughout the world.