 This distinguishes them from living nautiloides ("Nautilus" and "Allonautilus") and typical Nautilida, in which the siphuncle runs through the center of each chamber.However the very earliest nautiloids from the Late Cambrian and Ordovician typically had ventral siphuncles like ammonites, although often proportionally larger and more internally structured.The word "siphuncle" comes from the New Latin "siphunculus", meaning "little siphon".