Serpulorbis variabilis M. G. Hadfield & Kay, 1972 superseded combination Thylacodes variabilis is a species of worm snail common in the rocky intertidal in Hawaiʻi and the tropical Pacific.

[1] Thylacodes variabilis has a white-brown shell, which is coiled or partly straight and can reach a diameter of 14 millimeters.

The shell is often overgrown with coralline algae or coated with sand grains.

Like other members of its family, Thylacodes variabilis filter algae and detritus out of the water column as their source of nutrients.

[3] Females of Thylacodes variabilis brood their offspring in egg capsules that are attached to the inside of their shells.