Here you can find different leather and soft corals (Alcyonaria) and the horn corals (Gorgonaria), from the group of eight-rayed flower animals (Octocorallia). These, unlike the stony corals (Hexacorallia), have eight-rayed symmetry: The polyps always have eight tentacles, which are usually pinnate. With few exceptions, they do not form a solid calcareous skeleton, but only calcareous needles.
There are species with and without symbiotic algae. The former are very low maintenance, grow quickly at elevated nutrient concentrations, and are ideal for nano tanks and tanks requiring minimal maintenance.
The colorful azooxanthellate horn and soft corals are better left in the reef, because they feed exclusively on plankton and can only be kept alive in special tanks.