The reefs formed by Lophelia and other coral species develop over many hundreds or thousands of years. The upper levels of reefs support more recent coral growth with the densest accumulations of live Lophelia on the summit and upper slopes. The polyps work tirelessly keeping themselves clear of sediment, leaving the upper levels of the reef clean and pristine (See image of Lophelia reef on left).
But the live coral is just the tip of the iceberg, below lies the reef framework formed from the skeletal remains of previous generations of coral polyps. Over time this skeletal framework traps sands and muds to form a robust cold-water coral reef - ultimately these portions of the reef become home to the highest number of species (see the darker parts of the colony pictured left where other animal species can be seen).
The final outer portion of the reefs is often dominated by aprons of coral rubble extending around the reef. The coral rubble are the remains of the once living reef, broken apart by a combination of physical disturbance and the bioerosion of other animals that bore into the coral skeleton. The rubble habitats can extend for many metres around the base of the coral reef providing several sub-habitats.