shield for the ventral and dorsal parts of turtles (the order Testudines), completely enclosing all the vital organs of the turtle and in some cases even the head. It is constructed of modified bony elements such as the ribs, parts of the pelvis and other bones found in most reptiles. The turtle's shell is an important study, not just because of the apparent protection it provides for the animal but also as an identification tool, in particular with fossils, as the shell is one of the likely parts of a turtle to survive fossilization. Hence understanding the shell structure in living species provides comparable material with fossils.