ID this please

[bigcity51]

I am new to the hobby. Had a tank running for little over 4 months with 2 frogspawns and a hammer. I have noticed this creature pop up in my tank. Its relatively large about the size of a silver dollar and is the only one I see. Could you let me know if it is a danger in taking over my tank.

http://www.flickr.com/photos/15915662@N03/4149031338/

Thank you all for your help.

[jenjen]

Definitely aiptasia. Kill it!!!

[Ohiomom]

Yeap it sure is.also keep in mind where there is one..there is usually more..

[csal1-175]

X3 Aiptasia

[aquaph8]

nuke it good, so it doesnt spread. Thats pretty big for a majano. I would take the rock out and use aiptasia-x. I say take the rock out cause thats a big sucker and I wouldn't want it to spread. It may take a few treatments for that monster.