This is your brain on ecology.

If a ball goes off the left side, look for it entering on the right. It's the same for top/bottom. The balls really do go through a cycle. The entire picture is not a single cycle. I don't know how many are running. This may take a while to load. Wait for it. It's worth it. This is an example of a Rube Goldberg machine. You can see others HERE (click on the Artwork Gallery). An example of a Rube Goldberg machine you may have played with is the game "Mouse Trap". See a video HERE or a Wiki account HERE.