About Oxystele impervia (Menke, 1843)
The shell of Oxystele impervia ranges in size from 12 mm to 18 mm. It is an imperforate, rather thin shell with a conoidal shape. Its base color is typically whitish, pinkish, or bluish, and is marked with red, brown, or blackish coloring in countless patterns. These patterns usually follow one of several forms: dark longitudinal zigzag stripes on a clear light base; very obliquely descending narrow stripes or lines, which are generally zigzag or interrupted around the middle of the whorl; narrow spiral articulated bands around the middle of the whorl, with a mottled or barred base, and a suture bordered by a row of dark blotches; or a pink or purplish base color, with the entire surface variegated by fairly narrow spiral bands finely articulated with red or purple and white. The elevated spire is conical, and the sutures are distinctly impressed. When not eroded, the apex is minute and acute. The 6 whorls are convex and quite smooth on the outer surface, but if eroded, the underlying nacre is visible as finely spirally lirate. The base of the shell is not eroded. The aperture is very oblique. The acute outer lip has a narrow margin, is iridescent on the inside, and has a smooth nacre that appears lirate. The white, thin columella is arcuate and concave. It covers the umbilicus area with a callus pad, whose outer edge is usually not closely appressed to the shell base. The parietal wall has either a thin translucent callus or no callus. The outer edge of the umbilico-columellar callus is bordered by a more or less visible streak of blue, green, brown, or sometimes light yellowish. This marine species is found off the southern Atlantic coast of South Africa.
