Neopilina

Its anatomy[4] led researchers to believe that the cephalopods evolved from the Monoplacophora.[4]

Its pair of preoral tentacles are considered homologous to those of gastropods; like prosobranch gastropod tentacles, their nerves connect to the cerebral ganglia.[4] The post-oral tentacles are equated with bivalves' labial flaps, cephalopods' arms, and scaphopods' captacula.[4]

Cuticular hardenings around the mouth of the organism are considered to be jaw-like and not far removed from the beaks of cephalopods or the jaws of many gastropods.[4]

The presence of a single shell prompts comparisons to the cephalopod Nautilus, but besides its bilateral symmetry and direction of coiling, there is not a clear equivalence; Nautilus' shell is notably different in the possession of septa (and thus a siphuncle).[4]^:64 It bears a similar degree of similarity to most other mollusc groups, leading to speculation that it may reflect a relatively unchanged ancestral mollusc.[4] The shell itself is aragonitic, consisting mainly of a prismatic layer,[5] lined with nacre.[4]

The organism bears five pairs of ctenidia (gills), unusually for molluscs; the rear two are homologous to the two pairs in Nautilus. This is unlike the polyplacophora, who have a number of pairs of ctenidia, but this number varies and is not related to the number of their body 'segments'.[4]

The foot and pallial groove are very difficult indeed to discriminate from the polyplacophora,[4] supporting its placement in this group by molecular methods[2]

Its radula is not unlike that of the polyplacophora; notably, its fifth tooth is modified to be comb-like.[6]

Neopilina is a bottom feeder, probably a deposit feeder; whilst alive, its shell is covered by a layer of mucus that might be involved in feeding or locomotion.[7]