Is my polyp dying or infected?

Hi, over the past week, my coral isn't opening in some areas of it. And I've noticed they seem a little whitish, can anyone explain if this has happened to them? Are they infected? Are they just growing? Or dying? Water parameters Are all fine, PH 8.2 nitrate 0 Nitrite 0 Amonia 0.25

I've attached some pics.

Thanks

 

I think I see some white spots. Search Zoa pox (fungus or bacterial not sure). I had it and ended up losing my colony but others claim success with a regimented treatment. Not sure if this is what you have but there is many threads about it

 

Ok thank, I will look I to it.

 

What test kits are you using? How long has your tank been running? Ammonia should be 0. I'd check the accuracy of your tests.

 

Rules out the usual suspects as well. Zoanthid eating nudibrachs will be the most common, next Sea Spiders, Sundial Snails and some types of Asterina.