Unknown critters in sump

[Andrew Stevens]

Hello,

I have these unknown critters multiplying in my sump. Can anyone ID, and are they good or bad?

 

[vetteguy53081]

Hello,

I have these unknown critters multiplying in my sump. Can anyone ID, and are they good or bad?

I see sponge and pineapple sponge in which pineapple sponge are short lived and derive from silicates and filter feed off algaes and the sponge also favoring dark areas will grow and continue. The sponge can be removed easily by pulling or scraping off with edge of an old credit card or similar.