This species is sporadically common under rocks on shallow lagoon reefs, where it usually not associated with any echinoderms. We have, however, seen at least one specimen (bottom of page) that was on Holothuria hilla. The shell itself is a basic shiny white, slightly translucent, straight shell that resembles several species of Melanella, including published figures of Melanella cumingii. If the ID is correct, the gastropods.com website has a photo of a living specimen that exactly matches ours.
The one below was on Holothuria hilla.
Created 1 July 2017
Updated 27 June 2019