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It doesn't *look* like coralline in these pics, but there's an easy way to find out. Poke it! j/k, kinda. Try brushing it off. Coralline is hard and thin, cyano is soft, squishy, and will come off with a squirt from a turkey baster.
It came off so guess it is cyano. I got a rock last week with some zoas on it that had cyano and it cut it out, it must have spread.. Should i treat the tank with something?
First try to remove it all. I like to use combo toothbrush and airline tubing with siphon started to first brush it off, then suck it out before it settles somewhere else. If you're thorough, a few times doing this could get rid of it all. Follow that with a larger than normal PWC and really watch your feeding schedule and water parameters.
IF all that fails, use Chemiclean. But last resort, really. Requires going two days without a skimmer and a big PWC after that.