Crab ID

[Reefrus2003]

I found this in my tank the other day, the tank has been up and running over 18 years. The only crabs I have ever added that looked anywhere like these was emerald crabs, but I have never seen one turn dark colored or black. Is this just a older emerald crab maybe?

 

[themagicman]

It looks like some sort of Xanthid crab IMO. (bad)

 

[Reefrus2003]

I caught it this morning and moved it into the sump. I have lost a couple of sand gobies in the last few weeks. I have never seen this crab until a few days ago. It was munching on coralline algae.