Things just keep appearing in my tank! Help what is it?

[cwolf88]

I have attached a picture, but I just want to know what it is and if its ok for the tank!! I keep getting random new members and colors in my tank. I'm not sure where they come from, but every time so far I've been told they were great things for the tank! Heres to hoping that happens again! I have approx 9 of these in my tank now in various sizes! More keep appearing! Thanks so much!

 

[spanko]

Aiptasia sp. a pest anemone. Do a search above and you will find many methods to deal with them, but deal with them you must as they will overrun your tank stinging coral as they go along.

 

[old hickory]

Had a couple of these hitchhikers when I introduced my live rock. Bought a couple of peppermint shrimp and they were gone the next day.

 

[travelerjp98]

It's Aiptasia. If you plan to keep corals, I recommend getting rid of it right away.
They are a species of pest anemone.

 

[bugsman]

I had those same things that popped up on some live rock I purchased. I got rid of them though using Joe's Juice. I keep looking and so far after about 4 days I don't see anymore showing up.

 

[travelerjp98]

While feeding some of my larger aggressive fish, I've even seen aiptasia devour a whole silverside!