That airplane seat might look empty. But whip out a powerful microscope and you could spot this girl, perusing a microns-wide piece of SkyMall:
Oh, hello there—it's everybody's favorite skin flake-eating organism, the common dust mite. These little fellows, so despised for causing sneezing, itching, facial pain, and other allergic reactions in up to 130 million world citizens, are ubiquitous; they've been caught living it up in environments as extreme as the Antarctic and the International Space Station. It shouldn't be a surprise, then, that they're also using our jet planes to commute from country to country, as detailed today in a new paper in PLOS ONE.