What factors would affect anemone colour?

[Quinn]

I have two black saddlebacks hosting in it. I have never seen them take it any food, although the other day I dropped a pebble into the tank while I was doing some work and the female took it to the anemone. They don't do that with anything else that I know of.

I have tried feeding it two types of mysis, as well as raw prawn. It accepts neither. Yesterday I tried a piece of frozen mysis again and it looked like it was slowly moving to eat it when the female clown started banging the anemone, thereby causing the mysis to begin coming apart. As soon as my tang saw this it was in there and suddenly all my fish were going all out on the mysis magically emanating from the anemone. The anemone doesn't go for the food as fast as I understand it is supposed to.