Small white critter in filter area

[Lcombs]

I am new to this hobby. My tank is only four months old. I have a 24 gallon bio cube and noticed today that in the back area there’s little white critters attached to the wall/filter area. Was hoping someone could help me identify them to know if this is normal or harmful to my tank. I’ve posted a picture and apologize it’s not very clear but they are so small it’s hard to get a great picture of them but I’ll keep trying.

 

[Mike N]

They appear to be pineapple sponges. Just harmless filter feeders.

 

[sfin52]

I agree harmless.