A spiral
We find logarithmic spirals like this one in the shells; they are different from the archimedean spirals, which we can find instead over many buildings in Bolzano, for example palazzo Widmann, where we find one of the ten maths signposts of the project MIC "Maths in the City", in Bolzano, where this image has been used.
© matematita
immagine di Ester Dalvit
The image belongs to the sections...:
Some images of the maths signposts (Exhibitions with matematita)
Curves and lines (2D geometry)
Further information:
http://www.matematicaincitta.bz.it/