Naked eggs= use acid to eat away the outer calcium based shell of a raw egg. inner membrane will be left keeping the egg intact. A great way to learn about the structure of animal cells! Also a great way to learn about osmosis (the inner membrane is semipermeable. as the outer shell is eaten away, water is allowed to pass from the vinegar into the egg. the egg will expand. Add food dye into the vinegar. The dye will pass into the egg and you can see the diffusion/osmosis)!