sponge, coral, blob??

[bearwolf1]

Hi everyone.
I've lurked on here for a long time. I've registered to ask the esteemed collective what this thing is.

My tank has not received any new rocks in almost 3 years. I have found 2 of these growing in my tank. They were just "live rocks" from the LFS that looked nice and covered in coraline.

I'm certain they are doing fine for now, but was curious if they are a sponge (like I think) or something else.

Thanks

Richard

 

[bearwolf1]

Just for size reference, that is a keyhole limpet (I believe) on it and the very small feather dusters in the background.

 

[Anonymous]

Yup, sponge, or maybe a tunicate. This kind is very common on LR.

 

[bearwolf1]

Tangs!

:lol:

 

[Anonymous]

I would guess a tunicate as well. Very cool.
Andy

 

[Anonymous]

The more I look at this thing the more I'm convinced it is a colonial tunicate. Easiest way to tell is its texture--tunicates are slimy and slippery, sponges are, well, spongey and sort of prickly.