Single Candy Cane Head Dying

[TingeOfGinge]

I got this candy cane coral a few months ago. It's been doing pretty well overall, but this one one head has been slowly dying and I'm not sure why. The other three heads look great and are puffy during daylight hours.

Pictures aren't great, but I did my best. The left-most head is the sad one. The tissue on the bottom of the head is barely touching the rim of the skeleton opening and the rest is on the outer edge. The mouth is sometimes gaping and sometimes closed. The head itself never puffs up.
It looks like there's a pineapple sponge growing below the sad head. There's also a vermitid snail tube, but I glued that up a couple of weeks ago. The glue was taken off yesterday by my urchin, which it's now using as a hat!
I'm fairly new to this so I just wanted to make sure there's nothing I should be doing for it and if the head ends up dying, whether I need to do anything so that the rest of the coral will have a chance to survive.

Parameters:
29 gallon reef. Running carbon but no other additives. Other LPS and softies look happy. IO purple bucket salt.
Calcium: 412 (Hanna)
Alk: rock steady at 9.9
Salinity: 1.025
pH: 8.2-ish (Salifert, hard to read the colors)
Nitrate: 15-ish (Salifert)
Phosphate: 0.18-ish (Nyos, have a Hanna in the mail)


Thanks!

 

[Mr. Mojo Rising]

Doesn’t look like it’s dying to me. It’s not melting or turning white and I don’t see skeleton poking out. Personally I would just wait and see at this point.

 

[TingeOfGinge]

Doesn’t look like it’s dying to me. It’s not melting or turning white and I don’t see skeleton poking out. Personally I would just wait and see at this point.

The pictures don't do it justice, but the tissue is pretty receeded and the skeleton is showing around the top of the head. My plan was to leave it anyways and see what happened, but I just didn't know if I'd be risking the rest of the coral as well if I did nothing.

 

[kingranch2003]

Suspect number one is the vermitid snail. All other heads seem happy and the irritated head is directly above it. The slime web that they produce will keep the polyp contracted and eventually cause recession.

I started this colony as 2 small heads. Soon I noticed the same thing that you're experiencing. Upon closer inspection, I spotted several of these snails on the stalks of the corals. Manual removal plus bumblebee snails took care of them and the colony rebounded big time.