Large Red Contracting Hitchhiker- what is it?

[Boudreaux1945]

Hello-
There is a large red contracting thing on one of my live rock. It’s actually been there for a while-, but just noticed yesterday it contacts like a coral when touched. It reminds me of a shriveled red potato. It has a mouth.

 

[JonoB]

Looks like a sponge to me, but I'm no expert.

 

[Boudreaux1945]

Looks like a sponge to me, but I'm no expert.

Barrel Sponge is what someone said

 

[Sosuke]

.

 

[Sosuke]

Red Sea squirt I got a couple in my tank

 

[taricha]

tunicate
https://gulfspecimen.org/red-sea-squirt/

edit: what @Sosuke just said.

 

[Boudreaux1945]

Red Sea squirt I got a couple in my tank

That’s it! Thank you!!!!