Logarithmic Spiral

Logarithmic Spiral
The arms of spiral galaxies are roughly logarithmic, as are the bands of tropical cyclones and many biological structures such as shells. These are spirals which make a constant angle with the line connecting any point to the centre. Rays of light emanating from the centre reflect off the spiral and burn the image of a second identical spiral, slightly rotated.

References:
http://mathworld.wolfram.com/LogarithmicSpiral.html
http://en.wikipedia.org/wiki/Logarithmic_spiral#Logarithmic_spirals_in_nature
Story and image via Matthew Henderson 
More of his work: http://blog.matthen.com/