Gosper Curve

The Gosper curve (also called the "flowsnake") is a space-filling fractal discovered by Bill Gosper in 1973. Generated by an L-system, each iteration replaces every segment with seven smaller segments arranged in a hexagonal motif. At infinite depth the curve's interior — the Gosper island — tiles the plane perfectly.

L-system: A → A−B−−B+A++AA+B−, B → +A−BB−−B−A++A+B