Good or bad sponge?

[ducrider]

I have these greenish/blackish white tube sponges growing in both my nano and 90gallon reef tank. They seem to be growing pretty rapidly and I am worrying they will choke out my coral. Any ideas or suggestions. Here is a picture.

 

[GerritM]

That is an Carteriospongia vermifera.

Rather harmols sponge. That´s my opinion.

 

[taklein65]

+1 I have them in my tank don't seem to hurt anything.

Tim