Mathematics
Fractal
A geometric pattern that repeats at every scale—the same basic shape appears whether you zoom in or out. Fractals have non-integer dimensions and infinite detail.
Biological Context
Branching patterns in lungs, blood vessels, and trees are approximately fractal—similar branching appears at every level from major vessels to capillaries. Fractal geometry allows organisms to maximize surface area within limited volume. Coastlines and mountain ranges also show fractal properties.