Middle Devonian (lower Givetian) Calceola sandalina (Linnaeus, 1771) from Celechovice Limestone, Moravia, Czech Republic, displays sharply differing ontogenetic stages. Width of ventral side and size/volume of calice steadily increases in juvenile and adult stages but decreases in some specimens in final stages of life: we consider these reductive late stages to be gerontic characters. "Ventral" side of juvenile specimens is flat and straight while in adults this side becomes convex. We suggest that opening of operculum and shifting part of polyp body mass forward would shift centre of gravity so that calicinal part of adult coral could rock down to seabottom. Closing operculum would elevate calice above bottom. Rocking movements could help to free coral from sediment. Operculum positioning could move coral and keep it in optimum feeding position. Single specimen shows predation injury: almost half of the "ventral" side is missing between counter septum and corallite angle but has healed within calice.
Anthozoa, Rugosa, Calceola, Givetian, rugose orals, gerontic stage, epibionts, predation, regeneration, ecology.