reefin,
must be that hound does not like the way they look
b/c they are signs of good water, and also help through filter feeding, which also aids in maintaining better water, not to mention the fact that they are not a bad thing
now getting rid of them on the other hand, i don't know for sure, as mentioned, air will kill them, but also everything on the rock, so will poor water quality, or just scraping them off