With their opposing pattern, these two Fermat spirals are surprisingly beautiful. They look like something you might encounter in nature and yet result from a very basic mathematical formula.

Here's the Mathematica code I used to generate them:

(*Fermat's Spiral*)

width = 0.005;

graphColor = RGBColor[70/255, 137/255, 102/255];

k = GoldenRatio;

g[t_] := k*Sqrt[t]

PolarPlot[{-g[t], g[t]}, {t, 0, 15*Pi},

PlotStyle -> {{graphColor, Thickness[width]}, {graphColor,

Thickness[width]}}, PlotRange -> {{-12, 12}, {-12, 12}}, Axes -> False]