What is this?!?!

[nickenayat]

I was cleaning the tank today and noticed some weird sponge looking thing. It was connected by a fine line and would contract at times. Does anyone know what this is? Thank you

 

[DSC reef]

I'm gonna say sponge or tunicates. Harmless filter feeders.

 

[ZoWhat]

Leucandra

Read this article and half way diwn youll see this pic:

ARTICLE:
http://reefkeeping.com/issues/2005-07/rs/index.php