Coralline Algae: Orange disease!

[sunce_22]

There is no coralline algae underneath, it is just killing it! I read about it online, but there isn't much information about it.

It isnt the orange coralline algae, because is it only around the rim of the purple stuff and it moves then leaves the dead skeleton.

I have no bought any new rock, or exposed the rock to air. I guess I'll have to try to quarentine it, how much light does it need for the existing algae to survive?