Members of the Heterostropha; cone-shaped shell usually wider than high, with open umbilicus surrounded by a nodule-bearing spiral rib, sculpture of very regular spiral rings intersected by axial grooves or growth lines and, in most cases, a regular color pattern; shell circumference usually with 1 or 2 keels; columellar wall of shell aperture ("inner lip") with grooves; smooth protoconch separated from the teleoconch by distinct peritreme, heterostrophic (placed "up-side-down," with the axes of proto- and teleoconch diverging by less than 10°); first part of the initial teleoconch whorls with distinct growth mark; operculum corneous, built by spirally arranged lamellae, concave, flat or cone-shaped, always with peg-like projection on body side; radula small, five-toothed taenioglossate-like, or ptenoglossate-like with numerous marginal teeth, or replaced by large rod-like structure; mantle cavity divided by dorsal crest; foliobranch gill lamellae as epithelial extensions of hypobranchial gland; osphradium with semi-circularly arranged lamellae; gonochoristic, or protrandric to simultaneous hermaphrodites; in hermaphroditic forms, male, female and sperm-receptive parts with independent openings; modified sperm type with or without helically shaped para-crystalline component; planktic development with long-range veliger; eggs intercon¬nected by chalazae; predators on coelenterates.