Model of a nautiloid cephalopod.
Image: Benjamin Healley
Source: Museum Victoria
Fossil of the nautiloid cephalopod, Endoceras wahlenbergi.
Image: Benjamin Healley
Source: Museum Victoria
The oceans were home to a new type of predator – fast-swimming, jet-propelled molluscs called cephalopods, with keen senses and a cluster of grasping tentacles. The first cephalopods like Endoceras had cone-shaped shells. Later cephalopods had shells that were coiled or became enclosed within the body. This last group were the ancestors of modern squids, cuttlefishes and octopuses.