This algae is quite stiff and nearly impossible to pull or even scrub off the rocks. Manual remove just about requires scissors. I think it’s some kind of turf algae, but it doesn’t really look like anything in any of the posted ID guides. I’d like to know what it is and some suggestions on what to try to get rid of it. The emerald crab and tuxedo urchin only seem to eat it in small amounts but won’t touch the big mats (that I can see). Trochus snails don’t seem to impact it much either.