return of cephalopod of the day: endoceras

endoceras had a long, slender shell, with a small opening at one end and a larger opening at the other. the shell was made of chitin, a type of organic polymer that is also found in the shells of crabs and lobsters. the animal's body was contained within the shell, and it had tentacles and a beak-like mouth at one end. endoceras moved by jet propulsion, squirting water out of its mantle cavity to propel itself through the water.

endoceras lived in shallow seas and was likely a predator, feeding on small invertebrates and possibly even other cephalopods. it was a successful and widespread genus, with species found in north america, europe, and asia!

endoceras became extinct at the end of the middle ordovician period, along with many other marine species. it is believed that the mass extinction was caused by a combination of environmental changes, such as rising sea levels and decreasing oxygen levels in the water, and increased competition from other cephalopod species.