I store a little swivel desk stool underneath my ping-pong table in the basement and I noticed one day that the cloth on the chair looked like it had round water stains. I then folded the table sides up and witnessed a constellation of dust on the underside (on both sides).
I took several paper towels and cleaned it off. After cleaning, a faint imprint remains. It kind of has the consistency of spider webs. The dust invariably grows back in a few weeks.
I am simply curious as to what this is, because I've never seen dust in clusters like this (as opposed to a thin, uniform layer). I hope it is not mold or fungus. The room is relatively clean and I can't find this dust anywhere else in the room or under other tables. Why the ping-pong table?