White "tentacles" on my feather duster, is this a worm?

[Digiten]

Hi all! This is my first post here so I apologize if I do anything wrong!

The other day I noticed these white, translucent "tentacles" growing on the base of my feather duster. They almost look like roots growing on it. Is this a normal thing or an intruder? I googled around but couldn't find anything that quite seemed to fit the profile.

The actual feather duster doesn't seem terribly bothered by it. He still comes out, though not as much, and is most definitely still kicking (I was afraid this was him decaying initially).

This is a 75 gallon tank that currently just has two pacific cleaner shrimp, two Clarkii clownfish, and one carpet anemone plus the feather duster.

Parameters:
Nitrate: ~10 mg/L
Nitrite: 0 mg/L
pH: 8.5
Phosphate: >.25
Calcium: ~400 mg/L

 

[duberii]

Looks like a sponge- it can grow pretty fast but it's pretty easy to remove- just expose it to air for about 5 minutes. I personally don't mind them though

 

[Digiten]

Looks like a sponge- it can grow pretty fast but it's pretty easy to remove- just expose it to air for about 5 minutes. I personally don't mind them though

Good to hear its mostly harmless. Wouldn't exposing the feather duster to the air harm, though? If so would it hurt to let the sponge just... do its' thing?

 

[Maritimer]

The sponge should be fine, so long as it doesn't grow to interfere with the duster or anything else. If it gets that big, remove the part that's overgrowing something you like, and carry on.

~B.