PLEASE HELP IDENTIFY: Anemone, pest, or neither?

[loosfish]

These brown things grew from some liverock I got. Over the past year and a half, 4 have grown. The color isn't very pretty, but I like how they flow. I'm afraid they're a pest of some sort though, and would love if someone could identify them for me! They have a whiteish "slit" in their centers which appears to be a mouth but I have never witnessed them eating when i feed the tank with fish food or krill. If they are a pest, how do I get rid of them? Thanks!

 

[nikesb]

aiptasia in high flow.
you can try joes juice, aiptasia x, kalk paste. but if you can get a clean cut underneath their foot, that would be the best way cutting up the rock