These are growing/spreading in my sump

[bdejong1112o]

Not sure what these are. I have about 10 of them in random places in the sump. They do not appear to move and are stuck where they are. White in color and as shown below are in random locations. Any idea what they are and should they stay or go?

 

[Tahoe61]

Pineapple sponges, harmless.

 

[sfin52]

+1 on sponges.

 

[Idoc]

I have a ton of then in my sump and my overflow.

 

[Gareth elliott]

Once your tank is up for awhile, inhabitants like these help a lot with filtration. You will be surprised how much particles tiny sponges and feather worms take out of the water column. Every now and then will need to clean off pumps of them but small price to pay.