Description: Thallus encrusting to 5 cms or more in diameter with thin margins.

Habitat: Common, usually sublittoral, epilithic or epizoic, rarely epiphytic.

Distribution: Widely distributed around the British Isles. Europe: Portugal, Spain, France, Netherlands, Germany, Denmark, Baltic Sea, Sweden, Norway and Faroes. Greenland. Atlantic coast of North America: Canada and U.S.A. Further afield: Alaska and west Africa.

Similar Species: Stragularia spongiocarpa - the differences are microscopic. Ralfsia verrucosa differs having margins usually raised.

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

iNaturalist: Stragularia clavata at iNaturalist World Species Observations database.

WoRMS: Stragularia clavata at World Register of Marine Species.