Algae ID

[Sander1001]

Tank has been up for 18 months no detectable phosphates or silicates, have had red slime algae before, but this stuff is about the same color but not mat like. Red slime I could peel off, this stuff is thin and attached well to the rocks only. Any ideas what it is. The snails just seem to cruise over it with out eating any.

 

[jennifer24]

coralline? if it does not come off at all that would be my guess

 

[Triterium]

Is it fuzzy? I had some dense fuzzy algae that was pretty attached. Im not sure what it was but it didn't spread and I thought it was pretty cool.

Actually I think I heard somewhere that it was a form of corraline.