It's probably just the tint in your picture , but the mojamo I fight with is bright green. I make a thin paste out of kalkwasser and hot water and inject it into the mouth. Kills it instantly. The problem is: you can't get what you don't see and it grows behind rocks and continues to spread. I make it a monthly maintenance thing and try to stay ahead of it. Wish there was a way to treat the whole reef safely, but I dislike doing that. They say peppermint shrimp eat it, but that hasn't worked for me.