Aceol flatworm (Wamiona sp.) infesting bubble coral (Plerogyra sinuosa). The flatworms are orange and the bubble coral is white. The aceol flatworm is a phylum of acoelomates, which means that they have no body cavity. They have body fluids in between cells to help distribute nutrients, gases and waste products. Flatworms are found in marine, freshwater and damp terrestrial environments. Photographed in Lembeh Strait, Sulawesi, Indonesia.