Sponge/Tunicate on Decorator Crab

[Slapp]

Hello!
This attachment popped up recently. The little star closes up when you get near, the space behind it is a little smaller than a grape but bigger than a jelly bean:
Just wondering if my suspicions are correct, yes I know that’s a lot of Kenya tree.

 

[Double monti 61]

Not sure what it is? I have some sponge in my system and they do not react quickly although they change slightly probably in response to food but the response is very slow.

 

[DaJMasta]

Definitely a tunicate, I've even seen that coloration/patterning on gulf live rock on other tunicates. They will retract quickly when bothered, but generally open back up within a minute or two, whereas sponges basically don't react.

 

[Slapp]

Definitely a tunicate, I've even seen that coloration/patterning on gulf live rock on other tunicates. They will retract quickly when bothered, but generally open back up within a minute or two, whereas sponges basically don't react.

That’s exactly how they react. Cool, thanks guys.