LiveScience: Deep-sea corals are the oldest living animals with a skeleton in the seas, claims new research that found a 4,265-year-old coral species off the coast of Hawaii. Deep-sea corals , which are threatened by climate change and pollution like shallow water corals are, grow on seamounts (mountains rising from the seafloor that don’t reach the ocean’s surface) and continental margins at depths of about 1,000 to 10,000 feet (300 to 3,000 meters). These corals play host to many other …