Description: Encrusting and calcified to 2 mm (or more) thick without protuberances. The surface is smooth, the margin without orbital ridges. Conceptacles as pale discs with central pore elliptical, becomming burried witn age.

Habitat: Common on rocks, shells and Laminaria holdfasts in the low littoral into the sublittoral to 50 m.

Distribution: Throughout the British Isles. Europe: Spain, Iceland, Faroes and the Baltic. Atlantic coast of North America: Canada and Long Island. Further afield: Arctic Russia..

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

iNaturalist: Lithophyllum crouanii at iNaturalist World Species Observations database.

WoRMS: Lithophyllum crouanii at World Register of Marine Species. Accepted name: Lithophyllum crouaniorum Foslie, 1899. AphiaID: 371033.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Corallinophycidae; Corallinales; Corallinineae; Lithophyllaceae; Lithophylloideae; Lithophylleae; Lithophyllum