A big spot on my puffer (and it's not a spotted puffer!)

[jassz]

Hi,
I came home today to find this white spot on Olivander's nose (he's my Valentini puffer). It doesn't look like ick. It is a little bit raised right in the center. I wonder if he injured it, or maybe got poked by the lion fish? Or the anemone? He seems fine, not overly scared (of the lion fish or anything else and he has an appetite.

I have a 135g SW tank with a 40 gallon sump, protein skimmer etc. It is a FOWLR tank with a lion fish, a wolf eel, a picasso trigger and little Olivander. The pH is 8.2, SG 1.023, temp 82.2 and neg for ammonia, nitrite and nitrate.