A coralligenous habitat does not appear overnight. These underwater structures grow at a rate of 0.01 to 1 mm a year, comparable to the thickness of a hair or a sheet of paper. Slowly, very slowly, calcareous red algae lay the foundations, followed by sponges, soft corals and bryozoans. Each organism adds its own piece to the puzzle. These layers tell stories of the past: changes in light, depth and currents. Respecting coralligenous habitats means preserving centuries of living construction.

By filtering water through sponges, purple sea fans and other soft corals* that capture suspended particles, coralligenous habitats help maintain the clarity and quality of Mediterranean waters. Their solid calcareous structures stabilise the substrate, limiting sediment movement and protecting the seabed from erosion. Relief, cavities and sea fan branches provide shelter and breeding grounds for many species, supporting complex interactions between fish, crustaceans, molluscs and other organisms. Coralligenous habitats thus support local biodiversity and play a central role in the overall balance of Mediterranean marine ecosystems.

*Soft corals: often branching, colourful corals, such as red or yellow soft corals, that add structure and shelter to the seabed.