I.D. Help - what is this thing?

[The Fish Tank Hobbyist]

I have google searched and google searched and can’t find anything that looks like this!

Anyone have any idea what it could be?

Notes:

- Growing in a cave
- two pictures attached to this message - 1 picture a wide shot and 1 pic up close
- appears white
- almost looks like tentacles
- Tentacles are growing downward towards the sand

 

[Tired]

Sponge. Generally harmless. Some types can grow on corals and bother them. I have something that looks pretty much exactly like that. If it starts going anywhere you don't want it, just pull some out.

 

[ScubaFish802]

Is it possible you could post another picture under white lights instead of blue?

 

[The Fish Tank Hobbyist]

Is it possible you could post another picture under white lights instead of blue?

Sure can! How are these? Any better and thanks for the help in advance?

 

[The Fish Tank Hobbyist]

Also - for reference relative to the whole picture - the closeup pics that were included above are in the circled cave as pictured

AND it is pretty far back in the cave relative to where this “thing” is

 

[ScubaFish802]

Do they move? Only thing I could think of is some kind or worm or a sponge possibly.. hopefully someone else will chime in here

 

[The Fish Tank Hobbyist]

Do they move? Only thing I could think of is some kind or worm or a sponge possibly.. hopefully someone else will chime in here

They don’t appear to really move from what I can tell. Noticed this a few weeks ago and it’s gotten a smidge bigger since then

 

[Flippers4pups]

Sponge

 

[The Fish Tank Hobbyist]

Thanks @Flippers4pups

If it is. Sponge - how in the world could it have got in there if I did not put it in there? Any idea? Do they just miraculously appear? All my rock is actually marine pure synthetic rock and started dry from the factory.

Can sponges hitch hike on coral frags/plugs or something?

 

[ScubaFish802]

could be frags or if you have any snails etc.. I don’t know too much about them tbh