Traditionally the egg has been a symbol of life. It was decorated and left whole. But that was back when we didn't have indoor heat, which can contribute to raw egg exploding - not a pleasant smell!
It is best to work on whole eggs because they won't float when you put them in the dye. However, that's not always possible. I'll talk about prepping the eggs later.
Any kind of egg can be used — shown here is a chicken, goose, and quail egg.