Nudibranch ID?

[paradox_of_reef]

Just got this hitchhiker on a coral. The store owner said it was harmless and would eat algae but I have no way of knowing for sure. Can anyone ID this guy please?

 

[Betta132]

Not sure what it is, but it does look to have a gut full of algae. If it was on a coral, though, I'd be a bit suspicious of it.

 

[Sugar Magnolia]

Looks like an Elysia species which are harmless algae eaters.

 

[jraker]

I had the same on one of my corals but it was red. They are harmless

 

[pagojoe]

It's harmless.