Monoplex parthenopeus,[3][4] common name the giant triton or giant hairy triton, is a species of sea snail, a marine gastropod mollusk in the family Cymatiidae.

This species have been recorded as fossils from the Miocene to the Quaternary (from 15.97 to 0.0 million years ago).

[5] This species occurs worldwide including: The maximum recorded shell length is 180 mm.

The veliger larvae remain in the plankton for nearly 300 days, dispersing as far as 4000 km.

[8] This is the longest known larval duration and dispersal distance of any marine invertebrate which occurs along the west coast of North America.