If you look at Richard Ashbery’s Graphics Programming website, and in particular at the Animated Graphics examples, you’ll notice an animated GIF that isn’t included in the programs that can be downloaded from the site – but if you want to see the program in action, it is now possible to download it via !Store, in the form of a screen saver.
That GIF is described as a Butterfly Curve. The shape is formed from parametric equations – in this particular case, discovered by mathematician Telple H. Fay – which in programming terms can be squeezed into just two lines of code (although the program itself needs to be longer for other reasons).
