Today, living banks of the coral Cladocora caespitosa appear to be restricted to a few Mediterranean locations and are threatened by the escalating impacts affecting coastal areas. In this study the exceptional occurrence of the Mediterranean coral C. caespitosa in the Columbretes Islands Marine Reserve (NW Mediterranean, Spain) is characterised in terms of spatial distribution, cover area, colony size and growth rates. The coral colonies form beds and banks in rocky bottoms within a semi-enclosed bay that offers both hydrodynamic protection and high water exchange. The spatial distribution of the C. caespitosa colonies, from 5 to 27 m depth, is highly aggregated, depending on sea-floor morphology and showing up to 80% of substrate coverage. The annual corallite growth rates obtained through the alizarin red staining method and x-ray image analysis are similar, and range between 2.55 ± 0.79 mm and 2.54 ± 0.81 mm, respectively. The exceptional nature of these bioconstructions is due to their cumulative cover area, which is comparable in size to the largest C. caespitosa bioconstructions described to date in Mljet National Park (Croatia, Adriatic Sea).