Description: Filamentous, to 10 cms long, unbranched and uniseriate, somewhat constricted at the septum where cells are about as long as broad.

Habitat: Common in littoral rock pools.

Distribution: Common in the British Isles including the Shetlands. Europe: Mediterranean, Portugal, Atlantic coasts of Spain and France, Baltic Sea, Norway. Atlantic coast North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Virginia. Further afield: Arctic Seas the White Sea and Greenland, the Canary Islands, Jamaica and Alaska.

Similar Species: Chaetomorpha aerea and Chaetomorpha linum are very similar and considered, by some, not to be separate species .

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

iNaturalist: Chaetomorpha linum at iNaturalist World Species Observations database.

WoRMS: Chaetomorpha linum at World Register of Marine Species. Accepted name: Chaetomorpha linum (O.F.Müller) Kützing, 1845. AphiaID: 145027.

Classification: Biota; Plantae; Viridiplantae; Chlorophyta; Chlorophytina; Ulvophyceae; Cladophorales; Cladophoraceae; Chaetomorpha