The Cosmati were a Roman family, seven members of which, for four generations, were skilful architects, sculptors and workers in mosaic. Their name is commemorated in the genre of Cosmatesque technique a form of opus sectile ("cut work") formed of elaborate inlays of small triangles and rectangles of colored stones and glass mosaics set into stone matrices or encrusted upon stone surfaces. Bands, panels and shaped reserves of intricate mosaic alternate with contrasting bands, guilloches and simple geometric shapes of plain white marble.