Brown inverted cone that rises and falls

[Fishbird]

Hi again all,

I’ve just realized over the past 24 hours that this brown thing that I thought was dead macroalgae actually seems to be alive and extends, for lack of a better word, after lights are off. I noticed it extended for the first time last night and now it’s extending again since lights are off. Any ideas?

(I know about the GHA. I’m working on it.)

 

[El_Guapo13]

You tried touching it (with gloves on, gotta practice good safety measures) to see if it is hard or soft, or if you can pick it up and move it?

 

[Fishbird]

Hi sorry it's taken me awhile to get back to this thread. Anyway, the cone and the frilly bits on top are hard. I didn't press too hard when touching it because I didn't want to break it but it's definitely not soft or rubbery.

 

[El_Guapo13]

#reefsquad
@KJ

 

[KJ]

Bivalve?

bivalve mollusk - - Image Search Results

images.search.yahoo.com

 

[Fishbird]

Bivalve?

bivalve mollusk - - Image Search Results

images.search.yahoo.com

unfortunately it’s definitely not a bivalve. It doesn’t have a shell. It’s like a dense woven basket that rises up and down with a bunch of frilly wickerwork coming out the top. The frilly stuff fills the entire thing; as if you had a mug chock a block full of pencils.

At first it seemed to only come out/rise up at night but now it spends most of the time extended. It only withdraws if I put my hand into the tank to do a water change or something. You can also see that it seems to have lost It’s brown color in one patch. That area is white.

 

[TriggerFinger]

Is it a sea cucumber?

 

[35ppt]

Redacted

 

[Devin6871]

Could it be a colony of tube worms? Some species don't have complete concrete on of shell. If you could get closer pictures of it at rest and extension.

 

[StatelineReefer]

Calcareous sponge, not uncommon in gulf waters

 

[Fishbird]

The mystery continues. By now this animal has grown a pattern sort of like corduroy on its sides. Tonight it was open and the inside is white. While I was looking at it something white withdrew inside very quickly. The animal was still sticking up out of the rock but then the whole thing closed and pulled back into the rock. I’ve just never seen a sponge have this kind of movement to it before. And, it’s cone shaped with the frilly top but can also open along the side so it’s not really acting like any bivalve I’ve encountered either.

 

[Devin6871]

Well, that is super interesting. Some sort of critter using a trap door? I think it is time to strap a go pro to your tank and sift through recording

 

[TriggerFinger]

What about a tunicate/sea squirt?

 

[Riphter]

Could it be a bivalve that is wearing an algae/sponge hat? When it is lifted in those last set of photos what I can kinda see is what looks like a shell on the lower right hand side of the creature. When it’s opening the hat rises and when it closes the hat drops down.