I have always been fascinated by fractals - their infinite repetitive patterns are quite mesmerizing, and if you pay a bit of attention, you can actually find them lots of places in nature... one of them is the romanesco broccoli.
Actually the romanesco broccoli isn't a true fractal since it doesn't fully meet the criteria of infinite pattern repetition, but it's still fascinating and beautiful to look at... (and this one is going to be part of our dinner tonight).
