A word for the idea that simple life may be everywhere, and likely initially reached Earth from elsewhere, is 'Panspermia':

http://en.wikipedia.org/wiki/Panspermia

My hunch is that it's true: that when we get better at detecting it, we'll discover bacteria/viruses/spores of various kinds all over the place (including Mars and other solar system locales).

And perhaps less seriously speaking, I always thought this type of virus looks like a robot: http://www.cosmosmagazine.com/files/imagecache/feature/files...