It has been said that if the cells of all living things other than bacteria and fungi were somehow dissolved away, the remaining bacteria would maintain the structure of the living things. They are all around us, in us and on us. We can't help but contaminate everything we touch. I daresay if we met another sapient race on another planet, it would come down to a fight between their microbes and ours, and whose immune system could fight off the new microbes best. It gives a whole other meaning to the words "Germ Warfare".

If you don't care for reality, just wait a while; another will be along shortly. --A Rose