You may not be a spring chicken, but you still may not be able to figure out when the chicken laid the egg and what the expiry date is by looking at the stamp on the egg. If you are interested in finding out how fresh an egg is, here’s a little experiment for you.
You will need a small bowl and some cold water. If the egg sinks to the bottom of the water or only one end of it rises up slightly, you can eat it without worries. If it rises to the top of the water, you should throw it out at once, because it is unfit for consumption. The reason is, the eggshell is a porous material, which lets out moisture and lets in air. As the contents of the egg become dryer and denser, more and more air gets inside, making the egg becoming lighter over time.
***DIY source: www.onejive.com