Members of the order Testudines, sometimes classified as Chelonia, “turtles” is a broad term that includes three different types of these reptiles: tortoises, turtles and terrapins.
All chelonians share five traits in common that distinguish them from other reptiles. First, every species has a shell made of a carapace and a plastron. Second, all of them have four appendages. Additionally, they all have a tail, hatch from eggs, and have a specialized skull which lacks teeth.