Help!! Brain coral damage!!

[RockyroadReef]

Hi, I have this awesome piece if brain coral that I love, but noticed today that there is thus section of exposed skeleton on it. Does anyone know what could be the cause? It looks pretty healthy besides that.
Thank you!
P.S. enjoy the clownfish photo bomb

 

[JGT]

That’s a big chunk missing. Doesn’t look infected so that’s good. Could be one of your tank inhabitants munching.

 

[RockyroadReef]

Would fish suddenly do that? Because I've had this for a little while now and they haven't munched on this or any other corals in my tank, and I have mixed coral tank.

 

[najer]

Turn the coral so the damaged edge is getting no direct flow, fingers crossed.

 

[Beau_B]

If you don't have any suspicious fish, I would be looking at the CUC carefully. A rogue crab being the first in the line up.