Characters: Colonies are massive or form thick plates. They are meandroid with short, widely separated valleys interconnected with light blistery coenosteum. Septa are large, solid, smooth edged, exsert and widely spaced. Walls are solid. Columellae are absent. Tentacles are extended only at night. During the day the whole colony surface is covered with a mass of vesicles the size of small grapes and are grape-like or bifurcated in shape. These retract when disturbed. Colour: Pale grey, sometimes dull green. Similar species: Plerogyra sinuosa. Habitat: Turbid reef environments. Abundance: Common in protected habitats such as crevices and overhangs, especially in turbid water with tidal currents.