What is "bellerophontida"

The Bellerophontida is a taxonomic order of extinct marine mollusks that are found in the fossil record from the Lower Cambrian to the Lower Triassic. They are considered by some experts to be primitive sea snails with primarily symmetrically coiled shells, marine gastropod mollusks.

R.C Moore and J. Brooks Knight et al 1960 recognized bellerophonts as true gastropods, placing them as the suborder Bellerophontina in the sublass Prosobranchia, order Archaeogastropoda. Some more recent workers in the field have expressed uncertainty as to the taxonomic placement of this group.