The only surviving member of a large group of cephalopods which flourished over 100 million years ago.

The four species of Nautilus are the only cephalopods with an external shell. Very little is known about the life history of the Nautilus. It lives in the open tropical ocean ranging from the surface to depths of over 1500 ft. The Nautilus is commonly found in groups and actively feeds at night on crustaceans and fish.