Algae or bacteria?

[rongy]

New tank, but got those rocks from a cycled tank and they have been in my tank for couple weeks. Found those white/clear thing growing on them and still expanding. Is this a concern? I’m planning to add my first fish/coral this weekend

 

[taricha]

Those look like sponges - congrats.

 

[rongy]

Those look like sponges - congrats.

Beginner here. Are sponges good for LPS/Softies tank?

 

[taricha]

Beginner here. Are sponges good for LPS/Softies tank?

sponges are considered positive. Filter feeders that are cool and harm nothing.