Aquarium Corals by Eric Borneman
Caulastrea furcata is by far the most commonly available species, with bright colors, smaller corallites, and a slightly less packed array of polyps. Caulastrea echinulata has densely packed polyps, substantially larger and more oval-to-meandering-shaped corallites, and is rarely as colorful as C. furcata. The polyp tissue expands more in this species, often forming trumpetlike extensions from the skeleton. Caulastrea echinulata tends to resemble some faviids when expanded, because of the compactness of the corallites. However, there is usually space around each polyp that hints at the length of the long phaceloid branches. Caulastrea curvata is much more open in its configuration, with skeletal stalks sprawling outward. Greater space lies between the phaceloid stalks, and individual stalks often divide as they grow upward.