This thing is spreading quickly on this rock. It's also showed up on another rock about 3ft away. It doesn't seem to be attacking the discosoma mushroom next to it. What coral is this and how do I get this under control before it spreads to my other rocks?
I believe that’s some sort of antheila. Very invasive, and will take over a tank quick if left unchecked. Might want to consider completely removing the rock that it’s on.
Looks like purple star polyps. I'd manually remove as much as you can with a razor or your bare hands. There's much more extreme ways to remove invasive soft coral too, just know that you probably won't be able to get it out of the tank without taking the rock out and baking it in the sun.
Thanks guys. I took out the rocks today and added them to bleach and water to get rid of it. Will leave it in there for a week and then try to brush off as much as possible before putting the rocks back in the tank. I rather lose my beneficial bacteria and coralline algae in those rocks than have to destroy the entire reef later on.