Montipora encrusting spot with white string

[FullReefSurvivalMode]

Hello fellow reffers
1. Does anyone know what going on with my Montipora? The little fella has a spot that looks like a spot of dead tissue with a white string hanging out, did it just get attacked by a critter?
2. 3rd picture is that an Aiptasia? Super quality I know sorry
Best and thanks

 

[FullReefSurvivalMode]

75g DT 13g refugium 10g sump
8watt UV 24/7 filter sock skimmer ATO
Water parameter:
Alk 8,2 Cal 430 Mag 1350 pO4 0,06 NO3 12 temp 25deg/78 salinity 1,026 PH 8,03 no problems (besides

 

[fishface NJ]

A bit hard to see. Is it possible for you turn off your blue lights?

 

[REEFTIDE]

I agree with Fishface. You'll def want a little better pic(white lights will help) maybe even out of water