Plexaurella
The slit-pore gorgonians belong to the genus Plexaurella. They are all pale brown or yellowish, and form colonies with club-tipped branches. Large specimens may have many branches, but average sized colonies consist of a main axis and just a few branches, giving a shape like a big sahuaro cactus. These are very hardy and can be recommended as a "beginner's" coral. They must not be allowed to rest against the substrate, however, as the portions of branches that lay on the sand or against a rock will suffocate and rot, turning black and falling off the axis. Tips of branches under bright illumination (close to a 250 watt or 400 watt metal halide) may fail to open. This is a response to photosynthetically produced active oxygen. Shading will stimulate expansion of the polyps in this case.
Courtesy Julian Spring, Advanced Aquarist