Is my long tentacle plate dying?

[spoonman]

My long tentacle plate was fine yesterday, then this morning it didnt open up like it normally does. I am freaked! Is it dying? My ammo and trItes are 0 and my trAtes are around 20ppm. Mixing water for 10 gallon change right now. It is a 3 month old 29 gallon with live rock and canister filter. Salinity is 1.025.
Yesterday is looked like this:

Today is looks like these:

 

[spoonman]

Guess so.

 

[Nu-Nu the eel]

What has changed since yesterday? Waterchanges? Did you move it? Did it eat something?

 

[spoonman]

Fed it on Friday everything was fine it ate mysis. It looks like the mouth is destroyed.

 

[spoonman]

I am going to remove it from the tank. I am afraid it will poison the rest of the tank. Pieces are starting to float off of it. Should I have been dosing something? I do weekly water changes religiously. I don't know what happened. Emerald crabs wouldn't do that would they?

 

[spoonman]

Took it out of the tank. Looks completely destroyed.