A Very Fresh Egg
I have learned from my Food Technology class the practical way of testing the freshness of eggs. You’ll know that the egg is fresh when the yolk stays at the center.
An exceptionally fresh egg will instantly sink to the bottom and lie horizontal on its side. The reason is the air cell inside the egg is very small. The egg should also feel fairly heavy.
As the egg becomes not fresh and extra air enters though the pores of the egg shell, it will float and stand vertical.
This can easily be applied whenever you’re about to prepare some boiled eggs for your egg sandwich, for instance. You can immediately determine the freshness of eggs right there and then.