Leatherback Turtle
All sea turtles have large, hard plates--also known as scutes or scales--covering their shells. All sea turtles, that is, except for the leatherback.
The largest turtle on land or sea (she can reach 8 feet and weigh up to 1,500 pounds!), the leatherback doesn't have the hard shell that most turtles have either. Instead, the leatherback's shell is, well, leathery. This thick, rubbery shell is great insulation, allowing the turtle to travel in colder waters (think 30 to 40 degrees Fahrenheit, even in the summertime).