The Pinnotheridae are a family of tiny soft-bodied crabs that live commensally in the mantles of certain bivalve molluscs (and the occasional large gastropod mollusc species in genera such as Strombus and Haliotis). The earliest fossils attributable to the Pinnotheridae date from the Danian.

The Pinnotheridae are a family of tiny soft-bodied crabs that live commensally in the mantles of certain bivalve molluscs (and the occasional large gastropod mollusc species in genera such as Strombus and Haliotis). The earliest fossils attributable to the Pinnotheridae date from the Danian.