Go ahead and let them grow if you think they are cool. They will over run everything. Take care of them now before it gets out of control.maguay said:They did look like that, although the ones in my tank had more tentacles. However, they have all dissapeared. I'm not sure how but they're gone. I have noticed about 3 polyps that have sprouted though, and I know that is aptaisia. I Think they look pretty cool, are they really bad pest?