Tube structures

[kmanuele]

Anyone have thoughts on this one? It’s a cluster of green/brown tubes. Some sort of algae?

 

[KrisReef]

Perhaps a tunicate?

 

[KJ]

Agree.

 

[WheatToast]

Anyone have thoughts on this one? It’s a cluster of green/brown tubes. Some sort of algae?

Do they retract/close up when disturbed?

 

[Isopod80]

They appear to be the empty tubes of a previous colony of tube forming colonial hydroids. From the photo it appears the colony died off and left the tubes behind (possibly when the rock was dry). If any are alive you will see a small rosette of tentacles at the tips of the tubes. These would remain visible most of the time. Here's an example of a living colony.

 

[WheatToast]

They appear to be the empty tubes of a previous colony of tube forming colonial hydroids. From the photo it appears the colony died off and left the tubes behind (possibly when the rock was dry). If any are alive you will see a small rosette of tentacles at the tips of the tubes. These would remain visible most of the time.

Second! I have a few in my system:

 

[Isopod80]

Second! I have a few in my system:

Yup, there are a number of varieties. Some produce solid tubes like yours while others produce semi-translucent tubes like in the OP's photo.

 

[kmanuele]

Thanks guys, you hit the nail on the head

I had ruled out a sessile animal like a tunicate cus they’re rigid and don’t retracted when touched, but algae also seemed wrong.

So colonial hydroid makes a lot of sense.

Honestly kinda wish they were still alive, seem like cool little creatures

 

[Isopod80]

Thanks guys, you hit the nail on the head

I had ruled out a sessile animal like a tunicate cus they’re rigid and don’t retracted when touched, but algae also seemed wrong.

So colonial hydroid makes a lot of sense.

Honestly kinda wish they were still alive, seem like cool little creatures

Actually, be happy they're dead. The tube forming varieties can spread quickly and are a pain to get rid of. They can sting coral similar to aiptasia.