Foam
Macro shot of air bubbles on blue surface
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The foam on your morning latte is fractal. In nature, bubbles that occur when ocean waves break or where raindrops have fallen create a self-similar pattern with thin films of liquid separating various-sized gas pockets. Large bubbles are interspersed with small bubbles and those small bubbles interspersed with even smaller bubbles, and so forth.
Outside of nature, you'll see these fractal designs in a soapy bath or while doing dishes in the sink.