Homalopoma nocturnum
Homalopoma nocturnum is a species of sea snail, a marine gastropod mollusk in the family Colloniidae. Description. The size of the shell varies between 4 mm and 7 mm. The small, solid shell has a globose shape. It has 4-4½ rotund whorls, marked with subgranulose transverse ribs. The suture is obvious. The rotund aperture is iridescent and pearly within. The lip is thickened. Distribution. This marine species occurs off Southern Japan.