The shores of One Tree Island (OTI), Australia, are composed of coarse coral sediments and shell fragments. A vertical zonation of different colored carbonaters can be observed: the subtidal, the intertidal, the consolidated reef crest (also intertidal), the supratidal and the island zone. The composition of the microcommunity is responsible for the tinge of the carbonate rubble. Rock penetrating cyanobacteria dominate these specialized biocoenoses and each zone is constituted by different species. Studies by Gektidis (1997a) and Radtke et al. (1997) from Atlantic coastal regions show a surprising similarity in species composition.