We've begun to learn about this in my math class at school....I find it to be one of the most beautiful and exotic shapes in all of nature:

A figure of infinite resolution, able to be magnified forever because in the equation it uses, the solution becomes the variable for the next set. If you were able to zoom in on any part of the outlying shape you would begin to see amazing patterns and shapes. Occasionally you would see an exact replica of the original shape as you pass through the sets of the equations, and this would continue into infinity.