help with this ID please

[Monkichi]

I adjusted this picture to look like in real life. The thing growing on the skeleton of this hammer is a fluffy tea colored thing. There are a couple of smaller ones too. Is this just a harmless sponge or algae or something I should be worried about. Also, are the black spots harmless sponges? Thanks!

 

[Tahoe61]

The brown sponge should be removed from the tank. The black spots just look another variety of coralline. Every once in a while you come across an invasive sponge and that looks like one.

 

[Monkichi]

I took it off, texture seems more like a brown bubble algae than a sponge. I'll post this pic in Algae forum and see what happens.