Heterobranchia

Heterobranchia, the heterobranchs (meaning "different gill"), is a taxonomic clade of snails and slugs, which includes marine, aquatic, and terrestrial gastropod molluscs.

Rhodopidae is a family of sea slugs. Rhodopids are small, meiofaunal organisms with worm-like body plans that differ considerably from a typical gastropod body plan, to the point that Rhodope was at one point classified as a flatworm. They have no shell. Two genera are currently recognized within the family, Rhodope and Helminthope. Helminthope has been described as the most worm-like gastropod.

Murchisonelloidea is an unassigned superfamily of mostly very small sea snails, marine gastropod mollusks and micromollusks within the clade Mesoneura.

genus of gastropods

Nerineoidea is a superfamily of extinct sea snails, fossil marine gastropod molluscs in the clade Heterobranchia.