Sponges or something else?

[bkstang]

I've recently set up another tank and I noticed a several "sponges" on the rocks in a few places. Are these sponges or something else? I have sponges in another tank but apparently a different species. Should I be worried?

 

[litoreef]

Pineapple sponges .,. Nothing to worry about good stuff ..

 

[marrone]

They look like cu-tip or pineapple sponges.

 

[meherbas]

+1 on pineapple sponge

 

[reefiness]

Pineapple sponges with a fine dusting of silt

 

[bkstang]

Thanks to all