This community is found in the cracks and entrances to caves and tunnels, where the light is sufficiently dampened for the algae component to be very small or nil. It is formed by large colonies of bryozoans, sponges, ascidia, hydraria and segmented worms, and its development also depends on the food available. It is one of the most attractive sceneries of the sea beds.

Red gorgonia (Paramuricea clavata)

Red sea anemone (Actinia equina)

Other common marine organisms that can be found in this community:

• Snakelock anemone (Anemonia sulcata)
• Red precious coral (Corallium rubrum)
• Red starfish (Echinaster sepositus)
• Cardinalfish (Apogon imberbis)