Unknown algae/grass

[Swiftler]

So this stuff came in on a piece of LR and never seemed to be a problem. But lately I've noticed that it is growing longer and longer. It doesn't seemed to be spreading but I just want to know what it is, if it's good or bad for my reef, and if it's bad how to I get rid of it. Thanks

 

[Reefmob]

Mmm I'm sure whatever it is an emerald crab may munch it down !!

 

[Swiftler]

I have two emeralds in there already and they don't seems I get over there