Phosphoresce

I've always loved phosphorous, it's a wonderful little element on our periodic table and if you are being poisoned with it your vomit glows. Always a good thing to know, but then gain who examines their vomit that closely. Ferrem Sulfide glows as well but I prefer pure elements, god knows why. I just find in amusing tat things can glow.

We can all glow from time to time.... Without poison off course.