2-3.5mm. This small ramshorn snail is often overlooked due to its small size. It has rapidly expanding whorls and and oval mouth aperture. The shell can have strong, curved radial ridges but these are variable so not always very obvious. From the underside, the mouth is slanted back. Though the shell is a light brown, it is often covered in a deposit that makes it very dark.

Menetus dilatus has a more rounded mouth which is less slanted back.

Valvata crista has a mouth that is perfectly round.

Good images of both sides and a note of its size.

Slow rivers, canals, lakes, ponds and weedy ditches.

All year.

Common and widespread.

Uncommon or under-recorded.