And why are mites cool?

Well, they can help protect vineyards, for one thing.
And they increase plant reproduction (this was a study where they made simulated domatia and stuck them on plants; those kind of studies get me all interested because it involves a creative aspect).
And some people love mites so much, they dress up as mite domatia for a party in honor of Darwin's birthday

maybe you have to be a biologist to get excited about this kind of stuff, I don't know.

(Oh, and there is a drawing showing domatia here)