Shell 4-14 mm long, cylindrical to pupoid with shallow suture; aperture short, suture descending on last half whorl; labial edge denticulate or smooth within, usually extends past tip of columella; columella smooth with heavy anterior callus, some with transverse ridges; siphonal canal short; shell usually with fine spiral grooves.
Remarks. Gould (1860: 383) in his description called attention to the "curious curve of the suture near the posterior angle of the aperture, as if it had been drawn backward, thereby pulling back this angle and curving the last whorl downward." The pupoid shape, fine spiral sculpture and descending suture are the most diagnostic features for this genus, which has about 33 nominal species worldwide (MolIuscaBase 2018), mostly in the tropics.

Testa fusiformis, gibbosa, antice late truncata; apertura lunata, angulo postico callo impleto; columella simplici vitreo induta; sutura prope aper-turam abnormaliter arcuata. (Gould.)
Shell fusiform, gibbous, widely truncate in front; aperture lunate, with a posterior callus, columella simple, vitreous; suture abnormally arcuate near the aperture. The curious curve of the suture near the posterior angle of the aperture, as if it had been drawn backward, thereby pulling back this angle and curving the last whorl downward, is very peculiar. (Tryon, Manual of Conchology.)
TYPE. Aesopus japonicus Gould.
DISTRIBUTION. California, Lower California, Panama, Japan.