When I got my galaxea coral, I can't remember why I had it out of the water, but later on the evening my hand and arm hurt, like stinging. I later on connected it to the galaxea. It seems the slime it produces is not nice or something.
A Guy in my local club almost died from boiling zoas and the toxin went airborne, I'm not sure if he's even out of the hospital now. My Kenya trees give Me a rash if they are irritated and I wasn't running carbon, but anemones don't bother Me at all.
My hand and arm turn into an itchy hivey mess if they touch a couple of my corals, my rhizo, frogspawn and green toadstool all seem to cause it. Mild reaction will be a couple bumps on my fingers that irritate for a few days, this was from a tank rearrange and was weeks of annoyance.