Bet you think your face is pretty clean, huh? Well, too bad, because, as this exclusive clip from the National Geographic Channel's The Strange Truth explains, your face is actually crawling with tiny animal friends. But don't freak out — we talked to the two scientists featured in the clip, Julie Urban , PhD, and Daniel Fergus , PhD, of the North Carolina Museum of Natural Sciences, to find out a little more about these face "spiders."Although they are arachnids (a.k.a. invertebrates with eight legs), Dr. Urban says calling them face "mites" is more accurate than spiders. "They're so tiny that people tend to think they’re bacteria or single-celled organisms," says Dr. Urban, "but these are multicellular animals. They have to perspire, get oxygen, eat — they have complex body systems, but they can fit in the pores in your skin."Yep, it's true. Although there are two major kinds of face mites (different species of Demodex), we've all got some combination of them hanging out on our faces, whether we want to acknowledge them or not. Researchers first identified them back in the 1850s, but we're still learning exactly what it is that they do on our skin. Dr. Urban says they're gobbling up all the dead skin and excess oil on our faces. "They're like little tiny Roombas vacuuming up your pores," she says.Humans have been around for a few hundred thousand years, but the mites have got us beat — by a lot. Dr. Fergus explains that, in a recent paper , his team found that the mites split into those two Demodex species between 2.4 and 2.8 million years ago. And because they're so old, researchers can use them to find out more about humans. For instance, using DNA analyses, they found that people who share ethnic backgrounds tend to have more similar face mites.There's some research to suggest a connection between rosacea, a skin condition that causes redness and bumps, and the amount of face spiders on your skin. Specifically, people with rosacea tend to have more mites overall than those without rosacea. But that doesn't mean they cause the condition — it could actually be bacteria inside the mites that's responsible — or that you need to get rid of them. "If you’re not sick, they’re doing you no harm," says Dr. Fergus. (Still, if they really freak you out, Dr. Fergus says applying diluted tea tree oil will do the trick, though the mites will come back eventually.)To learn more about your face spiders and plenty of other strange but true tales of the world, check out the new season of The Strange Truth, which premieres this Sunday at 9 p.m. EST on the National Geographic Channel.