Cooperoceras was an odd genus of nautiloid cephalopod from the Permian Period. It looked like a spiny ammonite. Cooperoceras was about 4 inches long and 3 inches high. It probably had to avoid edestids, like Helicoprion, Parahelicoprion, and Sarcoprion, because their saw-like jaws could easily smash any kind of shell.
Since all Cooperoceras's living relatives, like squid, cuttlefish, octopus, and nautilus, are carnivores, scientists believe that Cooperoceras was also a carnivore which ate small animals such as echinoderms, bivalves, gastropods, and trilobites. Its spines were probably either for defense, telling each other apart, or attracting a mate.
Cooperoceras had a siphuncle and septa like Orthoceras. But unlike Orthoceras, it had a coiled shell which would have allowed it to live deeper in the ocean than an orthocone's shell would. Even though Cooperoceras had a coiled shell, it was not an ammonoid, because ammonoids do not have the operculum and Cooperoceras did. An operculum is part of the shell that can open and close to give the animal better protection from predators.
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