Zoanthids peeling off of rocks?

[blue_reefer]

Over the course of a few weeks, my zoanthids have been slowly dying. But they are not closing up like normal zoas. They seem to be peeling off of the rocks.

I recently stopped doing vinegar/carbon dosing, and I also did one dose of red slime algae remover. After that, I did a large water change. My sea hare also died in the tank recently (I couldn't find the body). Could the toxins in its body kill the corals?

Nitrates are close to 0.

In this photo, the large patch in the middle used to have zoanthids on it. Now they seem to be completely gone.

 

[Fylerb]

Any nudibranchs or spiders. Try and dip if possible

 

[AlSimmons]

I don't really have an answer for you, but I had a big colony of Green Bay Packers that did the same thing one time. (maybe 4" x 4") The rest of the Zoanthids in the tank seemed to be fine, but when I used some tweezers to remove a a few polyps they came off in a mat. (a lot of them) It was almost as if they weren't trying anymore. Weird!