(1):
(n.) Any species of Siphonaria, a genus of limpet-shaped Pulmonifera, living between tides, on rocks.
(2):
(n.) Any one of many species of marine shellfish of the order Docoglossa, mostly found adhering to rocks, between tides.
(3):
(n.) In a general sense, any hatshaped, or conical, gastropod shell.
(4):
(n.) A keyhole limpet. See Fissurella.