What is this white stuff on my rocks

[Impala67]

At first I thought it had something to do with the green hair algae growing with it but then it started appearing everywhere even on the glass and I don’t know what it is it seems to grow and it’s everywhere what is this?!!!

 

[BrianAnthony]

I would say it's a fungus as pictured here.

 

[oceanleaf]

They look like sponges to me.
They are harmless filter feeders. However, you seem to have a lot, so they might overgrow and suffocate your sessile invertebrates.
The amount of sponges and the presence of hair algae make me think your tank has too much nutrient, so you might want to consider managing that a bit to get both sponges and algae in control.

 

[Impala67]

They look like sponges to me.
They are harmless filter feeders. However, you seem to have a lot, so they might overgrow and suffocate your sessile invertebrates.
The amount of sponges and the presence of hair algae make me think your tank has too much nutrient, so you might want to consider managing that a bit to get both sponges and algae in control.

I’m not worried about the algae only on one or two rocks