soft coral

…of most hydroids, hydrocorals, and soft and hard corals, however, proliferate asexually into colonies, which can attain much greater size and longevity than their component polyps. Certain tropical sea anemones (class Anthozoa) may be a metre in diameter, and some temperate ones are nearly that tall. Anthozoans are long-lived, both…

Subclass Alcyonaria Octocorals. Polyps with 8 pinnately branched tentacles, 8 mesenteries, and a single siphonoglyph. Nearly all colonial with internal skeletons. Order Stolonifera Polyps of colony connected by stolons. Skeletons of spicules or horny external cuticle. Shallow tropical and temperate seas. Order

In some corals (Alcyonaria), spicules combine with fibres made of keratin (a protein also found in hair and feathers) or keratins with amorphous calcite (noncrystalline calcium carbonate) to form axial structures of great strength and size, enabling colonies to reach large bushlike proportions.