Sometimes obstructions are too large to dig around, so the mole must back up in its burrow. The hairs that cover its body are adapted for the occasion. Hairs on most mammals are shafts that point backward – so forward motion causes no problems – but the hairs stand against any obstruction to backward motion. The hair of moles, in contrast, is built with several bends, or strictures, that make the hair act like a spring. Only the top of the shaft, called the shield, is wide. If a mole moves forward the shield points backward, but if the mole has to back up the spring-like nature of the hair lets the fur compress for a moment as the shield reverses direction (microscopic view, photo).
This makes it easier for the mole to back up while in a tunnel. It also helps keep dirt from falling between the hairs. The resulting texture of the fur is velvety, and so soft that a kind of bandage for delicate wounds is called “mole skin.”