Toadstool Leather Coral (Sarcophyton spp.)
Leather corals are a soft coral with a rather tough leathery skin. They come in all sorts of attractive shapes and can be quite dynamic in the reef aquarium. They can change form by expanding and deflating their body or extending and retracting their tentacles.
They are considered to be some of the best soft corals for beginners. Many of the readily available species are easy to keep with great success. Yet advanced reef keepers also favor these soft corals, as they offer a nice visual balance to the tank. Many types of Leather Corals are easy to care for, especially corals in the Sarcophyton, Lobophytum, Sinularia, and Cladiella genera.
A number of the well-known “true” Soft Corals can also make great beginner corals. Besides the Leather and Soft Corals, there are hundreds of other different types of soft corals. These include Gorgonians and other unique Octocorals like the Blue Coral, Organ Pipe Coral, Green Star Polyps, and the Sea Pens. Each of these beautiful corals will have care requirements that are just as diverse as the animals they are; consequently not all soft corals are easy keepers. It is very important to learn about the species you are keeping for a successful reefaquarium.
Info from http://animal-world.com/
Pic from http://www.janetsreef.com/