Looks to my UNTRAINED EYE to be green hair algae and cuc to eat eat,urchins eat most algaes i believe and interesting little critters but there is algae id threads on this site if look
Nuisance Algae ID Guide. Red Slime, Cyano, Cyanobacteria. Green Film Algae, Film Algae. Green Hair Algae. Green Turf Algae. Bryopsis pennata and B. plumosa. Bubble Algae, Valonia. Lobophora. Blue Green Cyano.