Decorator crab with GHA?

[Sierra_Bravo]

So I'm assuming this decorator crab I inherited as a hitchiker has green hair algae, unless I'm mis-identifying it. I do not have GHA anywhere else in the tank. Is it a problem that he's running around the display tank with this much covering him? Will he spread it around?

 

[Cory]

Not sure about the crab but that's definitely green hair algae. And yeah itll spread.