Description: Small thin encrusting thallus, about 5 mm in diameter (40 mm on epilithic plants), smooth without orbital rings. Conceptacles flat or only slightly raised.

Habitat: Common. Epiphytic on Zostera, Chondrus, Furcellaria and other algae or epilithic in the littoral or upper sublittoral to 3 m.

Distribution: Throughout the British Isles including the Channel Islands. Europe: Mediterranean, Portugal, Atlantic coasts of Spain and France, Netherlands, Baltic Sea and Norway. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, New Jersey and the Caribbean. Further afield: Atlantic Sea (Baffin Bay), Canary Isles, Jamaica, Pacific coast of Mexico, Japan, Korea, Australia and New Zealand.

Similar Species: Other species of Pneophyllum.

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

iNaturalist: Pneophyllum fragile at iNaturalist World Species Observations database.

WoRMS: Pneophyllum fragile at World Register of Marine Species.