I can't believe I forgot this in my update above. I was scrubbing algae off with a toothbrush and got around the purple palys. They're really the only zoas/palys in the tank now. Did that at night and in the morning I came down to a sad looking tank. Both pincushion urchins dropped nearly all spines and I was sure they were going to die, but the black urchin didn't seem to be affected at all. My red Monti cap and the Jedi Mind Trick Monti were almost completely bleached and looked terrible. I can't remember right now what all else looked bad, but it was a sad day. All I can think of is it had to have been those palys. Can't say for sure though. It was interesting how really only those 2 monti's were affected, but not the branching monti's. And both pincushions but not the black urchin. It was so random. And the 2 monti's that looked terrible are on opposite sides of the tank, so it's not like it was localized. Anyway, good news is they both completely recovered as did the urchins! I really can't believe it, I was ready to pull them out. I won't be going near those palys again, that's for sure.
Those right in the center of the pic: