Orange Death?

[Kronk]

OK so I am pretty sure i have orange death on a rock in my aquarium. I have had the aquarium running a few years without any recent additions so i am not sure where it came from... Anyways its on the photo in the highlighted areas. I noticed it because its only on top of other algae, orange and looks really flaky. I seem to remember another canreefer may have dealt with OD before? does anybody have info on it?

I have removed the rock which sucks cause its big and has a ton of life in it.