Can anyone ID this critter.

[puffer9375]

This is growing on the bottom of a rock (no light). It is like a bag attached to the rock with the opening you see in the pic.

Any ideas?

 

[jennm]

Looks like sponge to me.

Jenn

 

[puffer9375]

I thought so to at first but that hole opened and closed when removed from the water. Feels kinda like squid mantle?

 

[Jaycen B.]

Sea squirt.