Spot A Good Egg
To avoid finding a yellow chick inside an egg instead of the yellow yolk you were expecting, use the following low-tech "x-ray" technique for a peek inside. "Candling" an egg refers to the very old practice of placing a candle or similar light source behind an egg and observing the condition of the air cell, yolk, and white inside. Today, we can use a flashlight for better visibility inside the egg, but an old-school candle can work just the same. Many species of birds (but not all) have translucent eggs. The light passing through can detect bloody whites, blood spots, or meat spots, and enables observation of germ development. Candling should be done in a darkened room or outside at night with the egg held in front of the lightsource at an angle, so the light doesn't shine directly into the eyes of the egg inspector. White-shelled eggs that are only a few days old will clearly show the yolk and white. Older eggs will have a reddish area with blood vessels extending away from it that resembles a big red spider. This is the embryo. If the whole egg is dark, there is a chick inside. That said, regardless of the stage of development, the contents of the egg are edible.