Shark skin has a rough texture due to small scales called dermal denticles, which are similar to teeth. These denticles are composed of dentin and enamel, and are innervated. They have a ribbed and layered pattern that guides water across the shark, reducing friction and drag, and helping the shark glide through the water. When rubbed from front to back, shark skin feels smooth, but when rubbed back to front, it feels like sandpaper. The denticles play an important part in swimming efficiency by channeling water across the fins and around the body, and breaking up the interface between skin and water, reducing friction between the two entities. The teeth also help protect the shark from injuries and several elements in the water, acting like a suit of armor. Shark skin is not made of traditional fish scales, and is characterized by its contrast between slippery appearance and rough tactile texture.