Bittium zebrum (Kiener, 1841). (Synonyms: Cerithium pusillum Gould, 1849; C. boeticum Pease, 1861b; C. paxillum Pease, 1861b; C. unilineatum Pease, 1861b.) Length, 5 mm; diameter, 3 mm. Shell: conic-elongate; with beaded spiral threads; brown, cream, or white with brown banding. Spire: protoconch of three white or brown whorls, the apical smooth, the next two carinate; teleoconch of five or six slightly convex whorls; suture slightly constricted. Sculpture: five spiral threads obsoletely to distinctly beaded; base with spiral threads; occasional varices on the whorls. Aperture: ovate; columella stout, glazed by a thin callus; siphonal canal prominent and projecting beyond the lip; outer lip thick, sometimes lirate within. Color: variable — white peppered with brown, white with a narrow brown spiral at the suture (B. unilineatum (Pease) ), light brown with darker brown banding (B. boeticum (Pease)), dark brown (B. paxillum (Pease)). Animal: exposed parts creamy yellow flecked with white and smudged with sooty freckles.
These cerithids are abundant on fringing reefs, less common in tide pools, and rarely found on benches or in sediments to depths of 15 m. They are rubble-associated, usually found under rocks. Pleistocene fossils are reported from Molokai (Ostergaard, 1939, as Cerithium boeticum).