Check out different kinds of eggs and you’ll see the difference between fish eggs, which are soft and have to be in the water to survive, and the eggs of land animals, which are hard so they can survive on dry land.
Now break open a chicken egg. The yellow part would be food for the baby chick, if the egg was fertilized (chicken eggs you buy in the store are not fertilized; no sperm came near them). The yellow part – the yolk – has a lot of protein and fat to feed the baby chicken. The clear part that turns white when you cook an egg is mostly there to cushion the baby chick, but it’s also food.