Biofilm? Sponge? Tunicates?

[killergoby]

I've had this film/tubey structure encasing this rock for at least a year now, and I'm beginning to get curious of what it is. When I removed the rock from the water when transferring tanks in July, the film felt slimey but did not readily brush off. It seems to be inflated almost like a halo over the rock, and resists any algae or other incursion. It survived at the bottom of a rock pile with likely little/no light, and in the current tank is in full intense direct lighting. It even resisted any incursion from a massive dinoflagellates outbreak that lasted for a month. Any ideas what it is? At first I thought it was a sponge or biofilm, but the complete lack of mobility and the presence of those tubes makes me question the biofilm theory.

 

[killergoby]

Here it is from a different angle (outlined in yellow). I'm thinking it may be some clear sponge? I don't see it pulsing so I'm not so sure about it being a tunicate. There are plenty of yellow/green sponges on the adjacent pillar, but I'm referring to the clear/white amorphous structure.

 

[najer]

Bump @ReefSquad ?

 

[Bleigh]

It’s hard to tell, but I’d guess a sponge also.

Does it have any kind of response if you poke it? (The famously scientific poke test.)

 

[KJ]

Sponge.

 

[killergoby]

It’s hard to tell, but I’d guess a sponge also.

Does it have any kind of response if you poke it? (The famously scientific poke test.)

No response to the poke test lol. Sponge it is! Weird that it survived being exposed to air so many times with no loss of tissue.

 

[Spare time]

I am following as I have one but don't know the species

 

[Spare time]

No response to the poke test lol. Sponge it is! Weird that it survived being exposed to air so many times with no loss of tissue.

Sponges can survive a lot of things. They have gemmules for asexual reproduction (I think its those) that survive drying out.