NOt surprisingly, there are natural control methods. However, in the confines of an aquarium, that usually means extermination, not really control. If you DON'T want zoanthids, there are several things you could potentially use.
Not to high jack this thread but I found these 4 things on a piece of rock I have. I know the one is some sort of tube worm but not sure what the others are. Any ideas?
The first looks like either a cluster of thin shelled bivalves or maybe some sort of byssal material (what is the texture?). Second looks like a worm of some sort, though I can't tell if the "tentacles" are pinnate or not. Can you confirm that? Otherwise, it may be a hydroid of some sort. The next looks like either a Gracilaria or Halymenia algal species. The last looks to be something similar to a Botryocladia alga.
I'll have to double check the first 2 and get back to you. The tube worm (?) hasn't opened in a few days, maybe it's a night time critter. Are the algaes ok?
Keep and eye on the algae. None of those are normally invasive (maybe except for the Botryocladia), but that isn't to say that they can't potentially become pests.