Pinnixa faba, known as the pea crab, mantle pea crab or large pea crab, is a pea crab[1] which lives harmlessly within a large edible clam. This species is a symbiont of Tresus capax and Tresus nuttallii in its mature stage.

Pea crabs, family Pinnotheridae, are small crabs that live symbiotically with clams, tube worms, sea cucumbers, and other fauna. Usually they feed on the results of their host's filtering, or in the case of sea cucumbers they live in the cloaca feeding off of the results of digestion and reproduction. They have no rostrum and no teeth between the eyes.