They began early in the Ordovician with Proendoceras or similar genus which had developed endocones, replacing the diaphragms of the ellesmerocerid ancestor.

The Proterocameroceratidae gave rise to the Piloceratidae early on, and later to the Manchuroceratidae and Chihlioceratidae, from which the Allotrioceratidae are derived, and later yet possibly to the Emmonsoceratidae and Najaceratidae.

Their shell was on one hand a carry over from some Cambrian monoplacophoran ancestor, passed on through previous orders, and on the other both a hydrodynamic facilitator and protection.

They could not have had fins for propulsion or steering, only the hyponome for spontaneous jet mobility and their tentacles by which to crawl across the sea floor and to grasp at things.

The diagnostic endocones in the early part of the siphuncle balanced the weight of the animal living at the front of the shell.