You can chip them apart with a flat head screw driver.
I would definitely frag off the dead heads.
Couple thoughts:
You just added a dwarf angelfish, have you seen it nip at these at all? My flame developed a taste for clams this past week
I have always had issues with Duncans if my tank was on the warmer side. 80F is a little high for a reef IMO/IME
Your phosphates aren't at 0, which is a) odd because you have SO MUCH macro algae and b) not good for any corals, and duncans, IME are not hardy to anything out of the norm for parameters
Your dKH and pH are both on the low side, duncans and acans don't like low alk levels.