Gorgonians are the sea fans. They are a type of octocoral with Gorgonin giving them structural strength. They are filter feeders and are often in areas with strong currents. There were many like this at Kashiragashima under a bridge with strong currents.
This bright Gorgonian with large polyps with 8 tentacles each. Enoshima
A red Sea Fan. Amami
A yellow Sea Fan. Amami
A red Sea Fan growing down from the top of a swim through. Amami
A small Gorgonian growing on a wall. Enoshima
Another Gorgonian growing on a wall. Enoshima
Close up of the Coral Polyps. Enoshima