Onchidiopsis glacialis is a species of small sea snail with a transparent internal shell, a marine gastropod mollusk in the family Velutinidae. Because the shell is mostly internal, the snail resembles a sea slug in general appearance.
The distribution of Onchidiopsis glacialis includes European waters.
The maximum recorded (shell?) length is 18 mm.
The minimum recorded depth for this species is 4 m; maximum recorded depth is 300 m.