That is sea lettuce. It is like crack for all clean up critters, fish included. Just get some herbivores and make sure you clean up their waste as they get the salad poops...
Looks like ulva aka sea lettuce. I don’t consider that as much of a nuisance. Manually remove as much as you can. Be cautious if you have a lot of ulva as the ulva may be acting like an in-tank refugium. Herbivores may eat ulva as gobyvin has said. You could also try to outcompete it using a sump refugium.
It is probably the most harmless macroalgae. I had a little show up for a short time in my office cube. I was sad when it got eaten or dissappeared. It is a pretty algae. I agree that you could outcompete with a refugium. I would try outcompeting with that algae in the refugium just as badbabyfry suggested. Transfer a few pieces from tank, add herbivores, and hopefully the display will get mowed as the refugium grows out to take over.