Testudines
Turtles are unmistakable. Their shells set them apart from all other animals. The shell is a modified ribcage and part of the vertebral column. It cannot be taken off (as cartoons would lead us to believe) anymore than you could take off your spine and ribs. Turtles lack teeth. Most are mute, but they have keen senses of smell and color vision. There are about 330 species of turtles worldwide.