Hydatina physis (Linnaeus, 1758)

Images taken at Chowder Bay, NSW, Australia

The shell is thin is creamy white with numerous black or dark brown spiral bands of varying width. The body is large with purple folds, an enlarged head shield and a foot that is much wider than the shell. The edging of the body is edged with almost luminous blue.

Species of Hydatina are very specialised worm feeders, eating only cirratulinid polychaete worms.