Help Id Unknown?

[Reddobie]

http://archive.reefcentral.com/vbulletin/showthread.php?s=&threadid=45870

[eudaimonia]

It looks like a sea slug to me. The herbivorous types usually camoflage themselves to look like whatever they're grazing on. So the fact that yours is green... well, it's encouraging at least.

Maybe you could try an experiment to see if it is reef-safe? You could get a small quarrantine or even a floating breeder box and place the sea slug in it along with an algae-covered rock. If the sea-slug eats the algae and survives, it's likely a harmless herbivore. If it dies, well evidently it wasn't herbivorous. No huge loss.

:)

[Nagel]

I would think its possibly a sacoglossan (sp?) type of slug. I had a few in my refugium (may still be there, dont see them often), and they eventually get to the main tank. Almost always they are on or near my feather caulerpa. The fact that it is green gives me reason to believe that it is a herbivore, as most of these critters tend to camoflauge themselves to look like what they eat.

Keep an eye on it, and try and get a better pic ( I know, if its like mine, its tiny, and the camera has a hard time focussing on it). I believe a good shot of its head will be helpful in a more positive ID though.

HTH