Simply fill a glass or bowl with cold water and submerge the egg. If the egg sinks to the bottom and lay flat on its side, it is still fresh. If it sinks but stands on one end at the bottom of the glass or bowl, it’s not as fresh but still edible. If it floats to the top, it shouldn’t be eaten.
The science behind this is based on the fact that eggshells are semipermeable, which means air can get through. So the older the egg, the more air can penetrate its shell, causing it to float.
