Fossarina patula is a species of very small sea snail, a marine gastropod mollusc or micromollusk in the family Trochidae, the top snails.

The shell is widely umbilicated, with alternate larger and smaller tuberculated spiral ribs.

The shell is whitish, sparsely maculated with dark brown.

The outer lip is ascending posteriorly.

This marine species is endemic to Australia and occurs off New South Wales, Tasmania and Victoria