Cocculiniformia are deep sea gastropods that have limpet-shaped shells (see example below). There are about 50 modern species and an unknown number of fossil species. Some modern members of this clade have a bizarre lifestyle: they feed exclusively on the beaks of decaying cephalopods (see Hartmann et al., 2011).
The relationship of Cocculiniformia to other major groups of gastropods remains uncertain and awaits molecular testing.
Families of Cocculiniformia
Gofas (2009) recognizes the following gastropod families and genera as members of the Cocculiniformia. This list was copied from the World Register of Marine Species (WoRMs) on March 3, 2017 and is reposted here in concordance with the source material’s Creative Commons BY 4.0 license. The link associated with each name will direct you to additional information about that taxon on WoRMS.
Family Cocculinidae Dall, 1882
Genus Coccocrater Haszprunar, 1987
Genus Coccopigya B. A. Marshall, 1986
Genus Cocculina Dall, 1882
Genus Fedikovella Moskalev, 1976
Genus Macleaniella Leal & Harasewych, 1999
Genus Paracocculina Haszprunar, 1987
Genus Teuthirostria Moskalev, 1976
Gofas, S. 2009. Cocculiniformia. Accessed on March 3, 2017 through WoRMS at http://www.marinespecies.org/aphia.php?p=taxdetails&id=156482.
Hartmann, H., M. Heß, and G. Haszprunar. 2011. Interactive 3D anatomy and affinities of Bathysciadiidae (Gastropoda, Cocculinoidea): deep-sea limpets feeding on decaying cephalopod beaks. Journal of Morphology 272(3): 259-279. Link.