Take the moon and wrap it in a bag and it will look just like a cell. It's a circle in a bigger circle. The moon is the nucleus. Yes! Science is happening!
As you learn about cells you realize they're all over your home (ほう). Without ever noticing it, your home has been slowly filling with dead skin cells. And now that you know what they look like (the moon with a plastic wrap bag around it) you can see them everywhere.