Something took a chunk off my alter ego Monti

[Joker Corals]

Does anyone know what Creature can took a chunk off on a Monti ? Or any worm ,bugs that eat it?

I only have tangs and clown fish in the tank.
Invertebrates : long spine urchin , arrow crab peppermint shrimp I don’t think is anything in my tank that eat it . So I think I t got be some type worm

 

[jda]

Which part are you looking at? It looks Ok to me, but I am probably looking in the wrong place.

 

[Joker Corals]