A Fractal which can be written as a Lindenmayer System with initial string "YF", String Rewriting rules "X" -> "YF+XF+Y", "Y" -> "XF-YF-X", and angle 60°.
See also Dragon Curve, Hilbert Curve, Koch Snowflake, Lindenmayer System, Peano Curve, Peano-Gosper Curve, Sierpinski Curve, Sierpinski Sieve
References
Dickau, R. M. ``Two-Dimensional L-Systems.''
http://forum.swarthmore.edu/advanced/robertd/lsys2d.html.