Despite appearances, goniatites are believed to have been surprisingly mobile. They were cephalopods, similar in body structure to squids and octopuses, which lived in a multi-compartmental shell. The animal only occupied the last chamber and propelled itself by using its tentacles or by squirting water out of its body cavity. The internal chambers of the shell were probably filled with gas, making the animal float and drift in water. Goniatites were especially widespread in the shallow seas that surrounded, and occasionally flooded, deltas in North America, Europe, North Africa and Australia.