sea hare

I recall a while ago that there was a sea hare making his way around this forum (sort of a continuous FIF). Well I have a hair algae / bryopsis problem that no amounts of snails/ hermit crabs/ tangs or water changes can fix. So I'm seeing if anyone has a sea hare that has done his job and needs...

Recently, I noticed one of these crawling around on my glass at 2am, (my lights were obviously off) any idea what it is? I noticed a second one the other day, I never see them on my coral. They seem to eat algae so I'll let them stay. :beerchug: