Here is a fossil ammonite in a creamy antique white color with fine details. It is the coiled shell of a 100-million year old mollusk, which has been remarkably well preserved. The ridges on the coils are sharply defined and stand up nicely from the surface, and there is little noticeable damage. These cephalopods lived in the seas and shared the same extinction date as the dinosaurs (the Cretaceous-Tertiary mass extinction event), and were probably a food source for mosasaurs. Ancestors of octopi and squid, ammonites used their tentacles to ensnare unsuspecting prey, much like their modern counterparts (there is also evidence to suggest some ammonites may have squirted ink to defend themselves against predators). The ammonite inhabited the largest chamber of the shell, whilst smaller segments were enclosed by septa and packed with air to help the creature float atop the open ocean.