Colpophyllia

Colpophyllia is a genus of stony corals in the family Mussidae. It is monotypic with a single species, Colpophyllia natans, commonly known as boulder brain coral or large-grooved brain coral. It inhabits the slopes and tops of reefs, to a maximum depth of . It is characterised by large, domed colonies, which may be up to across, and by the meandering network of ridges and valleys on its surface. The ridges are usually brown with a single groove, and the valleys may be tan, green, or white and are uniform in width, typically . The polyps only extend their tentacles at night.

==Description== thumb|left|An illustration of a Colpophyllia natans colony. Individual colonies of Colpophyllia natans are large and usually broadly domed, with curvature typically increasing with the size, and therefore age, of the colony. They grow up to in diameter and morphologically earn the epithet "boulder." Colony shape may occasionally be flat-topped discs, particularly when younger. As a type of brain coral, the surface of the skeleton is a network of winding, curving valleys and ridges (or walls) that roughly resemble the familiar folding architecture of the mammal cerebrum.