Hairy Mushroom Too Close To Zoa's??

[infamous]

I bought a second hand tank about 8 months ago and with it came a hairy mushroom. The mushroom is growing quite fast and it looks nice and healthy. I bought a couple of zoa frags a few months ago and they were doing quite nicely as well. About 3 weeks ago, the hairy mushroom has become increasingly closer to the frags, and now they have virtually disappeared. I haven't added any new fish or inverts recently, and haven't had a problem with anything eating the frags either. Would the hairy mushroom be "stinging" the zoa's at all? Would the mushroom growth be affecting the growth of the zoa's growth? Any input is appreciated!