noun Any of the headshield slugs of genus Bulla, belonging to the order Cephalaspidea of gastropods. A marine univalve shell of the genus Bulla (Bullidae) and certain shells of similar appearance of the now disused order Tectibranchiata of molluscs.
noun A marine univalve shell of the genus Bulla (Bullidae) and certain shells of similar appearance of the now disused order Tectibranchiata of molluscs.
noun Any member of the family Epitoniidae (syn. Janthinidae), of pelagic sea snails.