Description: Generally unattached branched thalli up to 1.5 mm wide which may be sparse or dense and are brittle. Attached forms have been found in the British Isles. Conceptacles only known in attached plants.

Habitat: Quite common. Generally sublittoral along with another coralline alga - Phymatolithon calcareum. Comprising deep deposits with living plants on the surface.

Distribution: British Isles in the south of England from Dorset, Cornwall and from the west coast of Ireland. Europe: Mediterranean, Atlantic coast of Spain and France, Baltic Sea and Norway. Further afield: the Canary Isles.

Similar Species: Lithothamnion glaciale. Phymatolithon calcareum detached branches of both species are quite hard and tough.

Key Identification Features:

• Forming unattached branching systems up to 5 cms in diameter.

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

iNaturalist: Lithothamnion corallioides at iNaturalist World Species Observations database.

WoRMS: Lithothamnion corallioides at World Register of Marine Species. Accepted name: Lithothamnion corallioides (P.Crouan & H.Crouan) P.Crouan & H.Crouan, 1867. AphiaID: 145165.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Corallinophycidae; Hapalidiales; Hapalidiaceae; Lithothamnion