Atys densus is a species of small tropical sea snail, a bubble snail, a marine opisthobranch gastropod mollusk in the family Haminoeidae, the haminoea bubble snails.
(Original description) The shell is small, oval, and thick, with a dirty white appearance. The surface is finely plicated and strongly striated in a transverse direction. Within the interstices, finer lines become visible when viewed under a lens. The aperture is narrow above but opens wide below. The outer lip is regularly arched; it is produced posteriorly, while anteriorly it is both twisted and produced, which allows it to partly cover the umbilicus.
This marine species is endemic to Australia and occurs in the Torres Strait and off Queensland.