What is "scleroplax"

Scleroplax granulata is a species of crab in the monotypic genus Scleroplax. It was first described by Mary J. Rathbun in a paper dated 1893 but only published in 1894.

Scleroplax lives as a commensal of various burrowing animals including the mud shrimp Neotrypaea californiensis, N. gigas, Upogebia pugettensis and U. macginiteorum, and the echiuran worm Urechis caupo (known as the " fat innkeeper"), and occurs from Vancouver Island, British Columbia to Punta Abreojos, Mulegé, Baja California Sur, Mexico.