Via the endlessly enjoyable It's Okay to Be Smart, here's a gif image that zooms in by about three orders of magnitude. (Not sure of the original source.) We start by looking at an amphipod, a tiny shrimplike critter about a millimeter across. For some reason (vanity?) it's decorated by an even tinier diatom, a bit of algae that is common in phytoplankton. From there we zoom in on a yet-tinier bacterium, just chilling out near the middle of the diatom.
Human beings have about ten times as many bacterial cells inside them as "human" cells. The bacteria are the passengers, we're just the bus.
