I LOVE finding new and weird stuff in my tank...and what is this?

[Subliminal]

Underneath a rock, around back, I found this thing. It was fully open when I looked and i just assumed it was part of the rock. But then I looked back again and the holes were closed. It doesn't seem to move, outside of the holes opening and closing.

Any ideas?

...and closed...

 

[Rtaylor]

Probably the siphons of a bivalve

 

[SaltyT]

It's a tunicate. I have some just like those on my live rock. Pretty cool finding new critters on your rocks isn't it?

 

[Subliminal]

It's a tunicate. I have some just like those on my live rock. Pretty cool finding new critters on your rocks isn't it?

Thank you! After looking up some pics, I think you're exactly right!