Why are my white zombies so white?

[Dj Medic]

They didn't used to look like this but they slowly started turning very white. They're on the sand surrounded by other zoas that I got so I don't think they're bleaching but I could be wrong. It gets around 100 par on the sand. There's 1 on the side that looks somewhat normal.

 

[beardedman11]

If you didn't have the one that looks like a true white zombie i would have for sure thought it was like a hawaiian type zoa. I would if you can try and frag that plug in half and put a frag up in higher lighting and the other in lower and see how they both react. I've had other zoas do the same thing in different lighting.