Demodex Face Mites

Demodex are arachnids about 0.3 mm long, far too small to see, and they live in the follicles of your eyelashes and skin. At night they slowly crawl across your face to mate, then return to their burrows by morning.

The oddest detail is how stripped-down they have become. A 2022 genome study found Demodex carry one of the smallest gene counts of any animal, having shed almost everything but the basics of living off you — and may be evolving from parasites into permanent, harmless residents.