matthen:

If you roll a circle inside one 3 times its size, it will actually trace out a 4 pointed star shape called an Astroid (this shape is traced out in the animation in orange).  But what if inside the smaller circle, there is an even smaller one tracing out a smaller Astroid?  This animation shows the intricate shape that is generated by adding the effects of all the Astroids.  [code] [also]