Tortoise shell is hard to protect from predators and the environment.   The shell is not a lifeless structure. It is indeed a hard structure but that does not mean it is made up of only bones! It is as much part of its body as a rib cage is ours. In fact, it is their rib cage, spine, vertebrae, and sternum with nerve endings and blood vessels attached to it. So, like human skin, its shell can send impulses of touch and pain to its brain. Basically, their skeleton is inside out, and just like we can't take our skeletons out of our bodies, tortoise skeletons can't be taken out either. It is made up of several bony plates called scutes that regrow to form new fortified layers of the tortoise’s shell and these scutes are connected to each other by a thin layer of skin.

Tortoise shell is hard because it is made of a protein called keratin, which is also found in hair and nails. The keratin in tortoise shell is arranged in a specific pattern, creating a strong and durable material. Additionally, the shell is reinforced by layers of calcium carbonate, which add extra strength and rigidity to the structure.