Possible sponges?

[Bethany97]

I picked up some new coral today and found a white/clear looking thing on the under side of the rock. It almost looks like a mushroom? But it could be a sponge, I guess? I honestly have no clue. I'm wondering if I should leave it, or take it off.

I was also wondering if all of the yellow growth is indeed some sort of encrusting sponge? Do I need to worry about it overtaking my tank in any way?

 

[KJ]

Sponge harmles . https://www.google.com/search?q=marine+sponge+-+ball&safe=off&rlz=1C1CHBD_enUS690US691&biw=1920&bih=955&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjYpNGDseTNAhVM02MKHYuAD-AQ_AUIBygCFilter feeder#safe=off&tbm=isch&q=marine+ball+sponge+aquarium

 

[saltyfilmfolks]

White and yellow are sponges I belive. No cause for concern.
The pink thing does look like a shroom.

 

[DSC reef]

Sponge is good, harmless filter feeder. I wouldn't worry about it taking over.

 

[jsker]

All of the above