Turtles & tortoises have hard, protective shells, made up of 59-61 bones. Like your bones, this shell is part of their skeleton.

The rabbit's digestive system is unique. It rests in its burrow   after feeding & passes soft droppings formed from partly digested food. It then eats these droppings to extract maximum nourishment from the food. Afterwards, it produces hard, pellet-like droppings which it deposits outside the burrow.

Rats' teeth are like razor blades and they can chew through almost everything, even concrete and metal

The first meal of a baby crocodile consists of several stones. Scientists think these are for ballast, to help crocodiles stay upright while swimming and/or to grind up food during digestion. 

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