Height 1.5 mm. Width: 5 to 7 mm. A small air-breathing freshwater snail. The shell is slightly glossy and rather thick, with close transverse striae, and is of a light horn colour. It has 6 to 6.5 rounded whorls which are evenly arranged in one plane, although the spire may be depressed and the lower surface rather concave. The periphery is generally only slightly shouldered above. There is sometimes a white rib around the inside of the mouth aperture, which is rounded, not oval.

The other small and tightly coiled species found in Leicestershire and Rutland is Anisus vortex. This has a strong angled keel around the edge whereas A. leocostoma is smoothly round, though may have a rounded shoulder..

It is commonly found in streams, ponds and ditches which dry out in summer, and in marshes.

All year round.

Common and widespread throughout Britain but less common further north.