Mytilus hirsuta Lamarck, 1819[1] Trichomya is a monotypic genus of marine bivalve molluscs in the family Mytilidae, the mussels.

It lives on exposed reefs and among rocks and seaweed in the intertidal and subtidal zone, attaching itself to hard surfaces using its byssus threads.

[4] It is an important constituent of the seabed fauna where it forms dense beds of tangled material providing a habitat for other species.

It was found to be much less tolerant to changes of water temperature than the mussel Mytilus edulis and the clam Mya arenaria.

In a study of nine different species of mollusc found in tropical marine waters, it was concluded that the hairy mussel was the most suitable to monitor pollution.