Leatherback sea turtle has a uniformly dark coloration, typically ranging from black to dark brown. Its shell is not as solid as the shells of other sea turtles and it has five longitudinal ridges along its back. Leatherback sea turtles can grow to be over 2 meters long and weigh over 900 kilograms. They lack a firm internal skeleton, and their shell is made of a thick, leathery skin that is reinforced with bony plates.