The hadal zone is the deepest part of the marine environment and it is the area of the earth that we know the least about. Because the hadal zone is so deep (20,000 feet and below) there are not many things that can live down there (where it´s pitch black, there is extreme pressure, and it´s generally very cold). As there is no light down in the hadal zone, most of the creatures that live down there don´t have any pigmentation (color) because why have color if nothing can see you? The most common hadal zone organisms include jellyfish, viper fish, tube worms, and sea cucumbers.