There are so many wild things living in the microbiome of a human's skin. Demodex are a great example; little mites that live near human hair follicles. They look horrific and they feed off of sebum, sweat, dead skin etc.

Many things are localized too; the things living in your eyelash follicles are not the same as the ones living on your elbows. We're a whole universe, and even our skin is colonized by bizarre little f*****s

Edit; a lovely little quote I found online, about Demodex

"When you sleep, the mites come out of your skin’s pores, mate, then go back into your skin to lay eggs."

Sexy.