The 'Alcyonacea', or the 'soft corals' are an order of
corals which do not produce
calcium carbonate skeletons. Instead they contain minute, spiney skeletal elements called sclerites. Thus they are not reef-building corals and do not lay new foundations for future corals. One type is dead man's fingers, which is a type that is no larger than 7 centimeters and is found in warm water regions.
Unlike stony corals, most soft corals thrive in nutrient-rich waters with less light intensity. Almost all contain and utilize
zooxanthella as a major energy source. However, most will readily eat any free floating food, such as brine shrimp, out of the water column.
Soft corals are readily imported for the reef aquarium hobby. However, because of their rapid growth under reef aquarium conditions, aquacultured soft corals are preferred over wild collected specimens. Often with a lower price and usually hardier aquacultured specimens are more practical.
Other organisms in the
Alcyonaria subclass include
sea pens,
sea fans,
sea whips and fleshy soft corals.

''Dendronephthya'' on a wall in Palau.

A close-up of an alcyonacean in Palau, showing the individual polyps.