Rocky substratum macrozoobenthic community that is present in confined waters of variable salinity (like harbours and lagoons) principally composed by the polychaete neozoon Ficopomatus enigmaticus Fauvel 1923 syn. Mercierella enigmaticus; in protected waters it may cover the entire hard substratum with a mass of erect, contiguous and intertwined calcareous tubes (up to 20 cm long). The reefs it builds constitute a highly tridimensional complex biotope (up to 50 cm thick), unique in the Black Sea and harbouring a diverse fauna from the other principal macroinvertebrate hard bottom Mytilus dominated community. Mussel juveniles sometimes attach themselves on the surface of the reef but never survive to adulthood. The dominant species of this community are Ficopomatus and Balanus while the numeric subdominance is attained by Palaemon, Xantho, Orchestia and Spaheroma (Micu & Micu 2004).