For a while now I have been wondering why the Sharingan, especially Sasuke's, looked so familiar then it occured to me just where I had seen that type of design before. I googled Atoms with three electrons and clicked on the images. Quite interesting some of those diagrams. Sorry that I'm not good with links, but hopefully some of the more adventurous among you will google it too...like I said, I think Kishi doodled in chemisrty class and his doodling ultimately gave rise to the Uchiha clan's "Atomic Eyes".