Comprehensive Description

"Acanthastrea forms large encrusting colonies or flattish to rounded heads. The coral has a slightly fleshy mantle and is green, brown or reddish in color. Tentacles are generally retracted during the day. Corallites are either separate and distinct or are united by their walls. They are usually polygonal but may be irregular or semi-meandrine with two or three mouths in a row. Calices vary in size within a single colony, but some at least are a centimeter in diameter and many exceed 2 cm. The fossa dips down several millimeters, and in the center is a small mouth. Septa are prominent and usually run from one calice to the next without interruption but may be separated by a small groove. The surface of the coral is rough and spiny to the touch. Acanthastrea is found in a wide range of bioteps but is not a common coral. Colonies may be a meter or more in diameter. There are probably five species." (Dr. Elizabeth M. Wood, 1984).