Lamarck's sheet coral
Milne Edwards & Haime, 1851
Colonies form large, mostly thick plates, broad, rounded or acute, often overlapping each other. The upper surface bears concentric rows of ridges with relatively wide, straight or reticulate, valleys. The white, star-like, polyps are in the valleys' center. The septa alternate in height and thickness. Generally, the taller and thicker primary septa extend close to the columella before dropping sharply into the corallite pit, while the thinner secondary septa appear shorter, because they slope gradually into the corallite pit. The underside of the colony is smooth, without polyps.
Yellow-brown to golden-brown to brown, sometimes with bluish or grayish tints, with contrasting white polyps.
Corallite diameter 3.1-4.5 mm, with 20-32 septa per corallite; septa alternate in height and thickness. Columella present, trabecular and discontinuous.
On sloping reefs and along walls, between 5 and 50 m, but most common between 20 and 35 m.
Occasional in Florida and the Bahamas, common in the Caribbean.