Fractals — patterns that repeat themselves so they look the same on every level — have often been found in nature. Here is a beautiful example of groundwater branching into streams at constant angles, creating their own exquisite fractal pattern.
Researchers from MIT noticed groundwater coming to the surface in streams which seemed to create similar patterns at every level, from the largest streams to the smallest capillary-like trickles. After analyzing the overall network, they found that the streams branched off at an approximate 72.5 degree angle. Since this fits quite evenly into 360 degrees, it created a five-fold symmetry, and a repeating pattern.
What results is this beautiful network of streams, reminding us of the role math plays in everyday life, even in things as chaotic as pouring water. Read the abstract here.