Rawhide

Rawhide is animal skin that has not undergone the process of tanning, by which skin is darkened into leather. The skin is devoid of all fur, meat, and fat, the resulting material often being pliable, translucent, and pinky.

As such, it is considered suitable for use in objects ranging from drumheads to lampshades, and is often used to make chew toys for dogs. Rawhide is also used to cover saddle trees, which make up the form or foundation of a western saddle.

Wet rawhide has been used by some earlier cultures as a means of torture or execution of enemies, gradually biting into flesh it's bound around. A strip of wet rawhide would be stretched tightly around the forehead of a bound victim and when exposed to sunlight the material would shrink; as the material dried when left unattended, the victim's skull slowly cracks as a result of the pressure.

Or wait, you don't need some random cultural detail explained to you, when everything you need to know about it is pretty much contextual? Then sorry. But admit it, that torture part, you're kind of glad you know that now, right?