Golden Snail

A happy snail whose shell spiral follows the golden ratio growth pattern: https://en.wikipedia.org/wiki/Golden_spiral

 

Shell chirality (dextral vs. sinistral) is determined as early as the 4-cell stage of development by the formin gene Ldia2, the signaling protein Nodal, and its target transcription factor Pitx.
http://www.cell.com/current-biology/fulltext/S0960-9822(16)30060-4

 

This shell spirals clockwise (dextral), the orientation that is more common and therefore more successful for mating but also more susceptible to snake predation. Which trait do you prefer?

http://www.livescience.com/9095-evolutionary-twist-snails-trade-awkward-sex-survival.html

http://www.nature.com/ncomms/journal/v1/n9/full/ncomms1133.html