Hard scales are protective structures found on the skin of certain animals, such as reptiles and fish. They are made of keratin, the same protein that forms human hair and nails. These scales provide a tough barrier against predators and environmental factors, helping to keep the animal safe and healthy. In reptiles like crocodiles and lizards, hard scales can vary in size and shape, contributing to their camouflage and defense mechanisms. In fish, such as sharks, hard scales, known as dermal denticles, reduce drag in the water, enhancing their swimming efficiency.