An adult Haminoea hydatis can be as long as 8–30 millimetres (0.31–1.18 in), while the shell reaches a length of 8–23 millimetres (0.31–0.91 in). It is a fragile, inflated, oblong shell partially hidden by the mantle and parapodial lobes in crawling animals. These herbivorous swimming snails are dark brown.
Distribution and habitat
This species is present in SW Britain, Ireland, France and south to the Mediterranean, Madeira and Canaries; Ascension Island, St. Helena and west coast of Africa. These snails live on muddy sands, shell grit and algae fields.
References
Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50: pp. 180–213