Five minutes ago I opened a bag of sandwich bread that someone of my family had forgotten (I suposse months ago) in my kitchen. The bread was completely green. So green it seemed some kind of fake bread. As far as I know, life has appeared there as form of bacterias. How is possible for that bacteria to appear without any other "interaction"? Where does the energy needed to perform this "birth" come from? How long can that bacterias (in that bread) live? Maybe stupid but, why green? Thanks to all replys.