Description: Unicellular sporophyte and a filamentous gametophyte.

Habitat: Common if looked for. Bores into shells and calcareous worm tubes in the littoral and sublittoral.

Distribution: Records scattered on the shored around the British Isles from England, Ireland, Scotland, and Wales and the Channel Islands. Europe: Portugal and Spain, France, Netherlands, Baltic Sea, Norway and the Faroes. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island and Virginia. Further afield: Pacific coast of North America, Caribbean, the Canary Islands, Japan, Australia and New Zealand.

Similar Species: The sporophyte is indistinguishable from other phases in the life history of Monostroma grevillei and Eugomontia sacculata and the gametophyte in Britain is known only in culture.

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

iNaturalist: Gomontia polyrhiza at iNaturalist World Species Observations database.

WoRMS: Gomontia polyrhiza at World Register of Marine Species. Accepted name: Gomontia polyrhiza (Lagerheim) Bornet & Flahault, 1888. AphiaID: 144903.

Classification: Biota; Plantae; Viridiplantae; Chlorophyta; Chlorophytina; Ulvophyceae; Ulotrichales; Gomontiaceae; Gomontia