Cantharidus fulminatus is a species of marine gastropod mollusc in the family Trochidae, the top shells.

It is narrowly perforate, shining, solid, smooth, except for a few stride around the white umbilicus.

Its color is pink, orange, purplish or olive-brown, generally with a series of white blotches alternating with self-colored darker ones below the sutures, a girdle of white blotches around the periphery and often around the umbilicus.

The intervening spaces are irregularly strigate with darker zigzag streaks or unicolored.

[2] It is a shallow water gastropod, found only off the Chatham Islands of New Zealand.