Habitat: Inhabit shallow reef tops, especially where wave action produces regular water movement. Numerous adjoining colonies can cover huge areas of reef tops. Most common between 15-30 feet. Distribution: Caribbean, Panama. Characteristics: Colonies form low clumps that resemble patches of leaf lettuce. The thin, upright blades have polyps on both sides. Wavy, parallel ridges run horizontally across the blade faces. Shades of brown to gray, often with yellowish or bluish tint. Blades fairly fragile.