Shark's teeth are flat and thin with serrated edges. Their teeth are essentially shield scales, which belong to scales, so they can regenerate constantly. Their teeth are not particularly durable, and they are used frequently, so they are prone to damage. After teeth are damaged, they will grow new teeth to replace the old ones. They often change their teeth, and even some species of sharks change their teeth all their lives. This high replacement frequency ensures the firmness and sharpness of their teeth and provides them with favorable tools for hunting food.