It's made of hard scales called scutes, that covers it carapace top of the shell and plastron bottom of the shell. One exception, however, is the leatherback turtle. Its shell is covered by a leathery skin. Sea turtles have no teeth, instead they have a powerful beak-like jaw that can crush, tear, and bite their food. They drink seawater, and the excess salt is secreted from tear ducts.
Sea turtles possess an excellent sense of smell.
Their hearing however, is more limited. There are no ears sticking out of their heads the middle and inner ear are buried inside each side of the head and are tuned in to low frequency noises. Sea turtles have good underwater vision, and are sensitive to visible and ultraviolet colors. But outside water, they are near-sighted. Adult males have longer tails, compared to females.