Cold-water corals

These are stony reef-building corals that live without sunlight, in cold dark water, feeding entirely on what the current brings. Two species build the frameworks: Madrepora oculata, which grows in a distinctive flattened zig-zag with white to pale orange branches, and Desmophyllum pertusum, better known to most divers by its old name Lophelia pertusa, which piles up into bushy white thickets. The big solitary cup coral Desmophyllum dianthus, a chalky white goblet on a stalk, grows among them, and over centuries the dead skeletons build a hard reef that sponges, brittle stars, crabs and deep-water fish move into.

Off the Maltese islands they are real but utterly out of reach. Living colonies and framework have been recovered from around 400 to 620 m, and the LIFE BaĦAR for N2K project's remote-vehicle surveys found stony reef corals most abundant deeper than 500 m. That is far beyond any diving, technical included, and the honest picture for a Maltese diver is that this is a habitat you will only ever see through survey footage.

They matter anyway. These are among the slowest-growing, oldest and most fragile habitats in Maltese waters, and the survey work that mapped them is exactly why Malta's offshore marine Natura 2000 sites were extended into deep water.