 Obviously, microbiome research is only one aspect of microbiology, but it illustrates nicely the general point of the philosophical richness of microbiological science. The occupation of humans by trillions of microbes means that traditional views of health, bodies, and even minds (according to some emerging research) need supplementing by microbial and microbiological perspectives. Because some of this new knowledge has only recently been revealed by large-scale molecular techniques, many of the strongest and most “revolutionary” claims require more rigorous conceptualization and analysis. But this is not exclusively a feature of microbe-associated science. Nor is the occupation of human bodies unique to microbes: helminths (worms) are historical human passengers, and are frequently argued to have system-wide benefits for their hosts that outweigh any harms (e.g., Lukeš et al. 2015). Nevertheless, we do not expect to see anytime soon a SEP entry on helminths. To clarify why, this essay will conclude by reiterating the several angles from which microbes and microbiology can be considered philosophically valuable.