ID please? either zoanthid or aiptasia.

[sunburnttikigod]

We just had this pop up one day during cycling our new 75 gallon tank. We're really worried it might be aiptasia, but curious it might be something really cool. any ideas? It has 8 arms and it hasn't moved but there are 2 smaller ones next to it.

http://imgur.com/4AnnwAr

 

[julie180]

Not positive, but it looks more like an anthelia or xenia than aptasia. Aptasia tend to be more clear while the corals are pinkish or brownish.

 

[billdogg]

I agree. I'm thinking green star polyp. But be careful - they can be every bit as invasive as aiptasia.

 

[joshky]

I was also thinking GSP, so that's my guess.

 

[Mcgeezer]

A little kalk paste will melt it into oblivion. Better safe then sorry. You don't want GSP or aiptasia taking over