All penguin species except the Emperor penguin build nests for their eggs. These nests can be made from a range of materials, depending on the bird's environment. This generally includes rocks, sticks, and mud. Emperor penguins have a pouch known as a brood pouch, which is a flap of feathered skin that can completely cover the egg. Balancing the egg on top of their feet, the egg is kept warm inside this pouch. Once hatched, baby chicks still take shelter in their mother or father's brood pouch.