Whats this? is it safe? How do I get rid if not?

[Martin Cox]

hi, got quite of few of these thing growing around my tank, what are they? What can I do? Do I just leave them?

How do I get rid of them either a method if needed or can I buy things to eat them? fish etc?

Any help, as always is greatly appreciated

[Reefing Madness]

Those are Aiptasia, a pest Anemone. Bad thing.
Aiptasia
There is a thing called Joes Juice. Or Use Lemon Juice and a syringe, you have to shoot it into the Anemones mouth to kill it, and cannot use a lot. Also, Peppermint Shrimp will eat them. CopperBanded Butterfly Fish will eat them.