Description: This oval to elongate oval reaches up to 5 cm in length and is dark brown in colour, and is usually mostly uniform with a few darker patches. It may be partially covered by the dark brown to olive periostracum. This may darken down to black in mature specimens. Conspicuous sculpture of concentric lines. Crossing these there are 12 ribs towards the front of the shell and 40-60 finer ribs towards the back. Inside of the shell pearly white with blue or brown tinges, and the external shell sculpture is visible.

Habitat: Sandy mud and clay, occasionally gravel from about 6 m down to considerable depth.

Distribution: Sparse records from around Britain and Ireland. Only record for Ireland is from just outside Belfast Lough, Northern Ireland.

Similar Species: Could be confused with Modiolula phaseolina, Musculus discors or Musculus subpictus. Could potentially be confused with juvenile Modiolus adriaticus, Modiolus modiolus, Modiolus barbatus or Mytilus edulis.

Key Identification Features:

• Dark brown with an oval to elongate oval outline.
• Concentric lines crossing ribs.
• Around 12 anterior ribs and 40-60 posterior ribs.

Distribution Map from NBN: Musculus niger at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Musculus niger at iNaturalist World Species Observations database.

GBIF data for Musculus niger

WoRMS: Musculus niger at World Register of Marine Species. Accepted name: Musculus niger (J. E. Gray, 1824). AphiaID: 140474.

Classification: Biota; Animalia; Mollusca; Bivalvia; Autobranchia; Pteriomorphia; Mytilida; Mytiloidea; Mytilidae; Crenellinae; Musculus