Have you ever noticed a weird, white string strung over your raw golden egg yolk? No need to worry--it's a good thing. That string is called a chalaze, and there are actually two of them. The chalazae (plural) can be found on both sides of the yolk, and their purpose is to hold the yolk at the center of the egg. The more prominent the "string" is, the fresher your egg--so really, you want to see the chalazae the next time you crack open an egg. If you don't, the egg is probably a little older--but most likely still A-OK to eat (you'll smell it if it's not).
The way to tell if your egg is too old and unsafe to consume prior to cracking it open is with this simple trick: Fill a bowl with cold water and place an egg in the bowl. If it sinks all the way to the bottom and stays there, the egg is fresh. If it floats to the surface, it's rotten and should not be consumed. Don't bother cracking it.
For more tips and recipes for cooking with eggs, click here.