Not sure about that dark spot, but the other spots are coraline algae which is normal. The coral itself looks pretty good. Let's get some other eyes on that dark spot. [HASHTAG]#reefsquad[/HASHTAG]
Not sure we talking algae here, I have the same or similar in my tank, dark red/Burgundy in color coralline.
The Monti is much stronger and will over power this.
I've had a Rainbow Monti talking over a 5" probably 40 eyes My Miami Hurricane in less than 4 months and killing it.