Micrelenchus purpureus, common name the red opal top shell, is a species of medium-sized sea snail, a marine gastropod mollusc in the family Trochidae.

[1] The length of the shell varies between 16 mm and 32 mm.

It grazes on seaweed.

This marine species occurs off North Island and South Island, New Zealand.

This Trochidae-related article is a stub.