Spirals in Nature

low pressure spiral
Low pressure system over Iceland. Image from NASA, taken on . 〔image source http://visibleearth.nasa.gov/view_rec.php?id=6204〕

Cyclones in general have the shape of equiangular spiral.

nautilus shell
A cut-away view of the Nautilus shell. Photo by “Chris 73”. image source

In general, Spiral-shaped growths in nature are mathematicaly equiangular spirals.

snail
A garden snail, showing equiangular spiral.

More photos of seashells at Beautiful Seashells Exhibition.

Cauliflower-3 2048
Romanesco broccoli, exhibiting equiangular spiral and fractal geometry. [Photo by Dror Bar-Natan http://www.math.toronto.edu/%7Edrorbn/Gallery/Plants/index.html]
Hawaiian fern; spiral
A Hawaiian ferm, exhibiting Archimedes' Spiral. [Photo by Dror Bar-Natan http://www.math.toronto.edu/%7Edrorbn/Gallery/Plants/index.html]

Man-Made Spirals

Samarra mosque
Great Mosque of Samarra, exhibiting Archimedean Spiral.
violin neck scroll volute
The neck of a unfinished violin. 〔image source〕

Such a spiral in ornament is called a volute.

spirals