Are grocery store eggs ever fertilized?

Hens do not need a rooster in order to lay an egg. A laying hen will lay almost one egg a day on its own.

These are the eggs that are sold for consumption in grocery stores. However, a hen does need a rooster in order to fertilize the egg. If fertile eggs are properly incubated for a few days, development of the embryo should be visible when the eggs are candled.

Moreover, federal regulations prohibit their use as human food. If fertilized eggs are not incubated, there will be no development of the embryo. Thus, there is no way to distinguish them from infertile eggs.