Within the coral scientific class Anthozoa is the order Alcyonacea, or soft corals. These corals typically grow in colonies of individual animals, or polyps, with tissue between the polyps. Unlike stony corals, soft corals do not produce a reef-building skeleton. Rather, they contain spiny structures called sclerites used as supporting flesh. Most species have a base stem and a branching tree-like structure that makes the colony appear as a single vertical organism. Many soft corals utilize a symbiotic photosynthesizing algae, zooxanthella, as a source of energy.
Soft corals are popular with both beginner and advanced aquarists -- creating a dynamic aquarium environment as they extend their polyps and move with water currents. They grow well in nutrient-rich water and do not require intense light.