The Droste Effect is picture appearing within itself.
The name comes from an old Dutch brand of cocoa Droste. Droste gained the name of this phenomenon by including it in the packaging artwork.
This self similar replication is often compared to recursion.
As a kid I would stare for long periods of time at images showcasing what I now know to be the Droste effect. In my opinion it is a good way to introduce the concept of infinity.