Their slender
shell is elongated with a pointed
spire. They vary in size from 3 mm (
Bittium alternatum) to 150 mm (
Cerithium nodulosum). The smallest shells are found in the subfamily
Bittiinae. The many
whorls have radial
sculpture with axial ridges and nodules. The
aperture shows at its base a vague curve or a distinct
siphonal canal. The aperture is closed off by a thin oval brown
operculum that is
corneous and
paucispiral. The palatal wall of the
aperture is somewhat enlarged and often shows a
varix. The
taenioglossan radula has seven teeth in each row. The single
rachidian tooth is flanked on each side by one
rhomboidal
lateral tooth and two long, hook-like
marginal teeth. ==Taxonomy==