Horses possess a single large toe on each foot, called a hoof. Modern horse hooves evolved over time from equine feet containing three or more toes.
A vestige of these earlier versions of the horse foot remains in modern equines, called the chestnut. The chestnut is a mark low on the inner leg of a horse. It is darker than the skin around it and covered by a tough hoof-like coating that can be peeled away like a scab. Early horses walked on their middle toes, and the toes on the side, such as where the chestnut is located, which became smaller with successive generations. Modern horses now retain only the middle toe, the rest of the toes to either side having withered away long ago.