Alcyna australis
Alcyna australis is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
Description
The size of the shell varies between 1.8 mm and 2.5 mm.The small shell has a broadly conical shape. The 4½ whorls are rounded and increase rapidly in size.
Colour: adult whorls dull white, protoconch dark purple.
Sculpture: the base is ornamented with spaced spiral grooves. These occur, but fainter, on the penultimate whorl. The protoconch, embracing 2½ whorls, is more
strongly spirally furrowed. The large aperture is round. Into it projects from the columella a prominent tooth-like tubercle. The contrast in colour and sculpture between the apical and succeeding whorls distinguishes this species.