Lithothamnion is a genus of thalloid red alga comprising 103 species. Its members are known by a number of common names. The monomerous, crustose thalli are composed of a single system of filaments which grow close to the underlying surface. Lithothamnion reproduces by means of multiporate conceptacles.
Underwater photos at Akrotiri 9/10/2016 by Kostas Aristeidou