Are these harmful???

I found still another new item growing in my tank.This time they appear to be either a different kind of paly or a small anemone.They are about the size of a zoa polyp, are dark brown with a deep green disk.The tentacles tend to grow out at an angle.I never had these till the last big piece of live rock was purchased.They are showing up in different spots. Good news on the other hand, since treating for pox all my zoas and palys are taking off like crazy.

 

Not like any of those.The green palys I have too, but they tend to grow from "Runners" into a colony.These are seperate individuals.Pretty but still would like to know what they are. Fortunately I haven't had and mojanos.I still have one or two tiny aiptasias in remote unreachable sections of the rocks.But they are either semi transparent or a pale brown.