Coral feeding. Hard coral extruding stomach filaments (white, translucent) to feed. Hard corals are capable of extruding long filaments from their stomach in order to feed. These filaments release digestive enzymes and any nutrients released are absorbed by the coral. They also use these filaments to attack and digest other corals as they grow and compete for the limited space on a reef. Photographed in the Lembeh Strait, Sulawesi, Indonesia.