####
Self-mating of the golden mean Siegel quadratic
polynomial, courtesy of J. Milnor.

One can get a 2-sphere by sewing two copies of this extremely wild
fractal (one in

blue and the other in yellow) along the boundary in a combinatorially
precise way.

See *Mating Siegel Quadratic Polynomials*,
J. Amer. Math. Soc. **14** (2001) 25-78.