Cotton ball like thing inside my sump

[stan450z]

I have noticed this cotton ball like thing in my sump - for a couple months. (this one is attached to the bottom of my protein skimmer. Anybody know what it is? Doesnt seem harmful but I am curious as to what this is. I also have 1 or 2 inside the bottom of my overflow.

Fish are fine, salinity normal, ammonia, nitrate, nitrite at 0. The areas obviously have no light at all, is it some type of fungus? Bad or good?

Picture attached of the one on my protein skimmer in my sump.

 

[mr_X]

Sponge.

 

[Richy35]

Hi it looks like some sort of sponge.

 

[stan450z]

Thanks, I assume it is not harmful then.

Guess it got introduced when I started adding the live arrogate instead of the crappy dead fine sand I was using before.

 

[mr_X]

Correct. Sponges are filter feeders and harmless.
Anything you purchased that came from the ocean could have brought sponge spores with it. Dry sand becomes live as soon as it's covered with bacteria. The fine sand you removed was most likely live before you removed it.

 

[kjboer7]

Thanks guys I have two just like it just there different colors I killed one of them when I was killing aipasia (spelling I know) so I guess I'll leave the others alone and see what happens