What's this hole?

[Fisherman Joe]

Bought this Symphillia at the weekend.

Came on some rock with dead barnacles on it but the White hole you see in this picture is not just a hole. It closes when stuff goes near it.

What is it lol?!?

It's obviously a coral of some sort, perhaps a sponge? But it closes very quickly.

 

[cloak]

Sea squirt or Tunicate perhaps?

http://www.saltcorner.com/AquariumLibrary/browsesectiongroups.php?SectionID=36

 

[Fisherman Joe]

Fascinating. Thanks.

Seems a shame it won't survive long.