There not bad, they are just one of the highly higher toxic palys, and they grow like weeds and will smother other slower growing corals likeother palys and everything, how I would rid them, either a kalk paste or put a rock right over all of them and they will wither away slowly, either or lots of carbon as they will be VERY toxic in the water column and keep your gloves on while doing this,, trust me you don't want palytoxin, it feels like death over and over again especially if you get it bad!!!, Ive been the victim a few times now to similar palys, be careful!!..!!..