Bathybembix aeola, common name the changing margarite, is a species of sea snail, a marine gastropod mollusk in the family Eucyclidae.

This system gradually dies out and leaves the surface smooth, only the row of infrasutural tubercles survives in an enlarged but depressed form.

Besides this larger system of sculpture, the whole surface is covered with minute, oblique, irregular, and interrupted puckerings of the epidermis.

The columellar lip is thin, spread out broadly at its base over the umbilicus, which it largely conceals, with a deep narrow furrow behind it.

It advances thin and pointed, curving over to the right to its angular junction with the basal lip.