Torch sudden recession, pest ID? Alk?

[NancyFish]

I’ll attach photos below. Pretty rough recession over the weekend, I’m thinking maybe from alk drop, but the photos look like there’s a pest flowing under the skeleton in 2 spots?

Our alk was running high, around 10.3, pretty stable for over a month (we had Dino’s and our alk consumption stopped for a bit) - stopped dosing and it took awhile before consistent intake started again, so I let it drift down naturally since. We’re back to 8.6 alk today. Wasn’t a major swing but again it went from alk number not moving to slowly dropping. Everything else has been consistent for the tank, no other LPs is bothered.

Any other advice or how to investigate it? Coral had coral rx and iodine dip 2 months ago, flesh seemed solid til now.

 

[smitten with ocean life]

@VintageReefer