What is this...?

[howdoo]

White, (maybe brown) stringy material on the rocks. Seems like they're stuck there as some of it is visible on the wall.

They're white in the walls and on some of the rocks whereas on others they look brown. Not sure if they're one in the same.

Obviously.... anything to be concerned about?

Thanks!

 

[Dburr1014]

Looks like sponge.

 

[howdoo]

That's interesting (for a fowlr)?!
If it is then no harm I'm assuming?

 

[Dburr1014]

That's interesting (for a fowlr)?!
If it is then no harm I'm assuming?

Sponge doesn't care if it's fish only. Unless you have fish that eat sponge.
Harmless.