Turtles and turtles are legged four-legged animals belonging to the reptile. The so-called Testudinata (or Chelonians) animal species is distinctive and easily recognizable in the presence of a hard and rigid 'house' or shell (bony shell).
This tortoise shell consists of two parts. The top that covers the back is called the carapace and the bottom (ventral, abdomen) is called the plastron. Then each part is composed of two layers. The outer layers are generally large and hard scales, and are arranged like tiles; while the inner layer of bone plates arranged tightly like a shell.
Exceptions are in the group of labi-labi (Trionychoidea) and the type of leatherback turtle, whose outer layer is scaly and replaced by a layer of skin on the outside of the bone shell.