Description: Solitary erect tufts to 30 mm long with, or without, short branches attached by spreading filamentous rhizoides. Uniseriate below and parenchymatous above, with short radial branchletsirregularly and alternatively branched.

Habitat: Now uncommon. Endophytic or epiphytic on algae and Zostera in low littoral rock pools and upper sublittoral.

Distribution: Widespread in the British Isles. Europe: Mediterranean and the Black Sea, Portugal, Spain, France, Netherlands, Denmark, Baltic Sea, Sweden, Norway, Faroes and Iceland. Greenland. Atlantic coast of North America: Canada, Massachusetts, New Jersey and Virginia. Further afield: Caribbean, the Canary Islands and Japan.

Similar Species: There are a number of similar small algae growing as epiphytes - all difficult to identify. Microscopic examination is required.

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

iNaturalist: Myriotrichia clavaeformis at iNaturalist World Species Observations database.

WoRMS: Myriotrichia clavaeformis at World Register of Marine Species.