ID please. Sponge? Or something else?

[ScubaSkeets]

Hi folks!!
Does anyone have any idea what this is? There a bunch of them on the underside of one rock. It's about the size of a pencil eraser. Some are a bit smaller and some are a bit larger. Sponge or something else? Thanks!

 

[DaJMasta]

I'd definitely go with sponge. If it reacts to touch, maybe tunicate, but from the structure I'd still expect sponge.

 

[ISpeakForTheSeas]

Yeah, that’s a sponge.

 

[ScubaSkeets]

Thanks. I thought it was a sponge but never seeing them in my tank before, i wasn't sure.

 

[kevgib67]

Yep!