Cylindrobullidae (listed in some sources as Volvatellidae) includes
small species with thin, lightly calcified shells that have constricted
apertures. Most are associated with green algae of the genus Caulerpa. However, the genus Cylindrobulla burrows in sand and
feeds on Halimeda. They often
emit a whitish defensive chemical when disturbed. At least four species
have been recorded from Hawaii in two genera (Cylindrobulla and Volvatella). Some authors place the
genus Cylindrobulla in its
own order, the Cylindrobullida.