Microbes

First thing you need to know for this story is that Ray Bradbury wasn’t stupid. The thing that’s most fascinated humanity about Mars, since we figured out what Mars was, is the idea that there might be life there. There’s a yearning, a deep longing that we not be alone in the universe, and a nextdoor neighbor might be nice. So, when Ray Bradbury was writing his stories about humans meeting Martians and discovering ancient Martian civilizations in The Martian Chronicles and other works, it wasn’t because Ray Bradbury was some dumb guy that didn’t know that old speculation about Martian canals had been debunked and the current science showed Mars to be a cold dead world. It was because he was a smart guy that understood that people needed and wanted the dream more than truth, the wonder of finding another intelligence just a cosmic cross-town bus away. Hey, even when they sometimes turn out to be hostile in science fiction, there’s still sort of a relief at knowing we’re not