We're surrounded and even occupied by microbes. All kinds of things live on and in us that are NOT us. But that's because we provide welcoming environments for bacteria (and viruses, too, but let's not go there).
Not all of the Earth is so hospitable to microbial life; consider the great depths of the oceans, where light and warmth and nutrients are hard to come by. Below that, in the lower oceanic crust, is the environment explored by Ginny Edgecomb of Woods Hole Oceanographic Institution.
She'll deliver the next geology lecture (online) at Southwestern Oregon Community College; we get a preview when she visits the JX.