I brushed my zoa and it's changed colour

[onlytoby]

Hey guys!
I'm currently going through a diatom bloom and after doing research I found that it's effecting my zoa, causing the skirt to curl up.
I brushed the zoa (around the base and on the polyp) to remove any dustings and of course it did close up. What I didn't expect is it's gone from light green to dark brown and has been for two days now.

Is this a normal reaction?
I've seen my snails all over the zoanthid before and it's never changed colour!

 

[anemoneanatomy]

Sorry to ask a potentially silly question, but: any chance your zoa has diatoms on it that are messing with the color? In general, could you post a picture?

 

[Just John]

Just curious what happened in the end. Is it still brown?