Horses are animals that we are very familiar with and love. They are symbols of speed and strength. Horses are also a common domestic animal. Many domestic animals have wild relatives, such as wild boar, bison, wild donkeys, wild dogs and wild cats. Surprisingly, it is difficult for domestic horses to find their wild relatives now, because these wild populations have completely disappeared. Wild horses live in a natural state on the grassland, can run, can dig the ground, and so on, and can also grind off their nails (horseshoes). However, when human captive horses walk, most of them walk on very hard roads, so they should wear horseshoes to protect them; Protect a horse with a horseshoe, and its toenails will wear out. In addition, after a period of time, horseshoes will also be broken, and it is necessary to repair horseshoes and re-nail horseshoes. Horseshoe, usually called horseshoe, is a hoof that grows from a horse's foot, just as the human body grows toenails to protect a horse's foot. Horseshoe is the toenail of a horse. Horseshoe belongs to the skin (stratum corneum) of a horse. The hoof is divided into four parts: the hoof edge, the hoof crown, the hoof wall and the hoof bottom. The hoof is also composed of epidermis, dermis and subcutaneous tissue, but there is no subcutaneous tissue on the hoof wall and sole. Source: Youth Science and Technology Expo (Middle School Edition)