Anyone know what this is?

[navvet8992]

This came on some live rock I got and has gotten bigger over the last few months. It’s attached to rock and looks like it has an open mouth now. Any ideas what this is?

 

[exnisstech]

Probably need pics under white lights for an ID

 

[argiBK]

Bumping as I recently received live rock that has a few of these as well.

My guess is it’s either a sponge or a tunicate. The ones in my tank have the ability to contract.

 

[ISpeakForTheSeas]

That looks like a solitary tunicate to me - harmless filter feeder.

 

[navvet8992]

After looking it up i do think it’s a tunicate. It has the mouth opening on the end. Very cool! Thanks guys!