Description: Thallus small and tuft-like. Filaments monosiphonous and no more than 2 cms high, rising from a solid cushion of 2 to 4 cms in diameter.

Habitat: Not uncommon. Generally epiphytic on Cystoseira or Halidrys in the low littoral and upper sublittoral.

Distribution: Generally distributed around the British Isles except the east coast of England. Europe: Mediterranean, Portugal, Spain, France, Netherlands, Baltic Sea, Norway, Faroes, Spitzbergen and Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island, New Jersey, Delaware and Virginia. Further afield: Indo-Pacific.

Similar Species: Other species of Elachista and other small tufted algae require microscopic examination for identification.

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

iNaturalist: Elachista flaccida at iNaturalist World Species Observations database.

WoRMS: Elachista flaccida at World Register of Marine Species.