Presumably this is an animal. Whitish blob on live rock.

[Tired]

About an inch and a half across, came in on some Gulf live rock in November. It hasn't changed since then, and doesn't visibly respond to light, touch, or food. It's very dense and hard to the touch, enough that it makes a 'thunk' sound if tapped with something, but isn't quite as hard as something like a marble. It seems to be pretty resistant to algae growth, and is smoother than any coral I'm aware of. There's a structure of some sort inside it, though I don't know if that's gill/digestive type filaments or a hard skeleton.
Tunicate? Sponge? Saltwater fungus? I'm really thrown by the lack of any visible vents, holes, or other ways for it to breathe or filter-feed. Planning to look at it tonight after lights out and see if it's changed in the dark- maybe it opens up to breathe at night.

 

[EeyoreIsMySpiritAnimal]

About an inch and a half across, came in on some Gulf live rock in November. It hasn't changed since then, and doesn't visibly respond to light, touch, or food. It's very dense and hard to the touch, enough that it makes a 'thunk' sound if tapped with something, but isn't quite as hard as something like a marble. It seems to be pretty resistant to algae growth, and is smoother than any coral I'm aware of. There's a structure of some sort inside it, though I don't know if that's gill/digestive type filaments or a hard skeleton.
Tunicate? Sponge? Saltwater fungus? I'm really thrown by the lack of any visible vents, holes, or other ways for it to breathe or filter-feed. Planning to look at it tonight after lights out and see if it's changed in the dark- maybe it opens up to breathe at night.

No idea but following!

 

[Spare time]

No idea but following!

Lol same

 

[EeyoreIsMySpiritAnimal]

Can we try a biopsy?? Poke a small needle in it and aspirate what's inside? Do you have a microscope?

 

[V A R I A N T]

I think it’s bubble anthelia. It’s gonna pop, release anthelia spores and take over your tank!

I have no idea but am also intrigued!

 

[Tired]

I've considered stabbing it somehow, but I don't know if it's something that will be harmed by stabbing, so I'm a bit reluctant to do that unless I know for sure that the stabbing would be useful for an ID.

 

[Reeflix]

im following so i can figure out what this is!

 

[Kathy Floyd]

#reefsqad

 

[AydenLincoln]

I think it’s a sea squirt/tunicate! @ISpeakForTheSeas thoughts?

 

[TnFishwater98]

I’ve got a big one. Figured it was a sponge . I’ll get a pic
* Lights aren’t bright enough yet

 

[TnFishwater98]

I think it’s a sea squirt/tunicate! @ISpeakForTheSeas thoughts?

It’s not a sea squirt. I’ve got those also. This is my guess

 

[Sailaway]

It’s not a sea squirt. I’ve got those also. This is my guess

That would make sense, I’ve seen those on gulf rock before.

 

[TnFishwater98]

This is a sea squirt

 

[Tired]

There are an enormous number of species of tunicate/sea squirt, in an absurd number of shapes and sizes. Some are solitary, some are colonial. I have probably half a dozen different shapes of them on this rock. One thing that they consistently have in common is easily visible intake/outtake tubes, and they'll also generally react to touch by scrunching up.

Chicken liver sponge looks fairly similar, particularly in texture. "Odd, hard sponge in this general group of sponges" seems like a reasonable ID for now.

 

[ISpeakForTheSeas]

I'm not sure. Possibly a Galeommatid (family Galeommatidae; "Naked") clam? Some of them (like Chlamydoconcha orcutti) look relatively similar to this when retracted - and that would explain the hard texture - but typically (from what I've seen) they also have one visible "tube"/hole sticking out.

 

[Shon]

Looks like "sea pork" to me. Which is an ascidian (tunicates and sea squirts). They come in many colors also.

If you Google Image search: "Florida sea pork" You'll see a few that look like it.

Edit to add: https://www.atlasobscura.com/articles/what-is-sea-pork-blob.amp

 

[TnFishwater98]

Here is one that came on some Gulf Live Rock about 3 years ago. It wasn’t this big when I first got the LR. Didn’t even notice it. One day just looked under the LR and saw this white blob. It’s doesn’t get alot of light. Im still thinking Chicken Liver Sponge. But not 100%. There are way more knowledgeable reefers on here that could verify.

 

[Tired]

I'm not sure. Possibly a Galeommatid (family Galeommatidae; "Naked") clam? Some of them (like Chlamydoconcha orcutti) look relatively similar to this when retracted - and that would explain the hard texture - but typically (from what I've seen) they also have one visible "tube"/hole sticking out.

Too non-reactive and tubeless to be one of these, but what a cool animal.

Looks like "sea pork" to me. Which is an ascidian (tunicates and sea squirts). They come in many colors also.

If you Google Image search: "Florida sea pork" You'll see a few that look like it.

Edit to add: https://www.atlasobscura.com/articles/what-is-sea-pork-blob.amp

I've seen this article, and there are definitely some similarities. The article doesn't mention density, though, and I imagine a lot of those blobs would look different in the water. Tunicate was my first thought for this, but tunicates generally seem to have some sort of visible breathing tube.

Here is one that came on some Gulf Live Rock about 3 years ago. It wasn’t this big when I first got the LR. Didn’t even notice it. One day just looked under the LR and saw this white blob. It’s doesn’t get alot of light. Im still thinking Chicken Liver Sponge. But not 100%. There are way more knowledgeable reefers on here that could verify.

What does it feel like if you tap it? Definitely looks like roughly the same thing, and I've settled on "something like a chicken liver sponge" as an ID for my own particular lump.