Pea crab Meaning, Definition & Usage

  1. noun tiny soft-bodied crab living commensally in the mantles of certain bivalve mollusks

WordNet

Definitions
  1. (Zoöl.), any small crab of the genus Pinnotheres, living as a commensal in bivalves; esp., the European species (P. pisum) which lives in the common mussel and the cockle.

Webster 1913