Clownfish hosting in large M Cap

[winnham]

We have two false percs that have been in a tank with a beautiful purple anemone (long tenticle) for about 5 months now. I have never seen them even notice it. We added a very large (about 8-9 in long with several "layers") orange m cap last month and now the clownfish are hosting in it! My question: will this harm the m cap in any way? Also, both percs were the same size when we purchased (fairly youg and less then 2 inches long) one has grown significantly more than the other -- I suspect the small one is the male. Am I correct in assuming this? Thanks in advance for any input.