Description: Thallus growing from a small holdfast to 40 cms long, pinnately branched, usually in one plane though sometimes irregularly, hollow. Not segmented but branches taper at base. Colour brownish or pinkish.

Habitat: Common. Epilithic or epiphytic in the lower littoral and sublittoral to 20 m.

Distribution: Widespread around the British Isle from the Shetlands to the Channel Islands. Europe: Mediterranean, Portugal, Atlantic coasts of Spain and France, Netherlands, Baltic Sea, Faroes, Norway and Iceland. Greenland. Atlantic coast of North Atlantic: Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and New Jersey. Further afield: Morocco, the Black Sea.

Similar Species: Gliosiphonia capillaris and Lomentaria orcadensis.

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

iNaturalist: Lomentaria clavellosa at iNaturalist World Species Observations database.

WoRMS: Lomentaria clavellosa at World Register of Marine Species.