So, I’ve had a box of uranium glass marbles sitting around the house for a decade or so, but it wasn’t until recently that we got a black light and could see them glow. Uranium glass is glass with uranium mixed in, duh, which gives it a pretty green color. Under ultraviolet light, it fluoresces.
I was sitting at the dinner table and glanced at the shelf where the box of marbles sat. A thought popped into my head: “You still have that black light for spotting urine where Starlight peed inappropriately, right?”
Carole affirmed that we did, and the rest is history.
Here’s what that box of marbles looks like in regular light:
Here’s what it looks like in ultraviolet light.