The deep sea, the abyssal zone - between 4 and 6 km deep, lives extremely slowly. It also recovers extremely slowly. Traces of machinery pulled into the deep sea for Peru decades ago are still there as they were then. Companies are responsible for restoring their mining area to its original state after the operation. Several recolonisation experiments are ongoing. One experiment, by NIOZ, Netherlands, deployed frames with artificial nodules to test whether this would help restore the ecosystem after mining.

From: Recolonising the Deepsea