Like sea anemones, corallimorphs are solitary polyps, although they are usually found in groups forming carpets.
Corallimorphs are distinguished from sea anemones and corals by an having upturned mouth in the centre of the oral disk in contrast to an inward turning mouth.
Corallimorphs also have a narrow body column, although this is usually hidden by the broad oral disk. The body column is usually buried in the ground or attached to a surface. Some corallimorphs tuck their oral disk into their body columns when they are exposed out of water, so they look like blobs. These can sometimes be seen on the seawalls during low tides.
Their internal structure is similar to that of hard corals. But unlike hard corals, corallimorphs don’t produce a hard skeleton and lack long tentacles.
Corallimorphs usually have two types of tentacles: one type found on the edge of the oral disk and another kind on the surface of the oral disk. Their tentacles are usually short, some so short that the tentacles are merely bumps.
Corallimorphs come in a wide range of colours and textures on the oral disk. Most corallimorphs harbour zooxanthellae (symbiotic algae) inside their bodies like coral polyps. Corallimorphs also produce toxins that seem to injure or kill hard corals or other encrusting organisms that settle near them.
Corallimorphs are secondary colonisers that rapidly cover empty spaces in a reef, e.g., dead corals. Corallimorphs are more resistant against pollutants and are thus used as indicators of pollution.
Source: Wikipedia
Beaded corallimorph (Discosoma nummiforme) (Singapore)
Carpet corallimorph (Rhodactis indosinensis) (Singapore)
Frilled corallimorph (Rhodactis inchoata) (Singapore)
Stubby corallimorphs (Singapore)
