help me id a crab!

[fresh]

Hi all,

I bought an acro, and with it came a crab. He is fully white in colour and his eyes are black. There is a black line on the forehead that connects the eyes and also a black line from each eye that goes from the eye towards the back of the body.

I kept him in a glass of tank water until I can identify if he is good or bad and decide what to do with him. Any help would be greatly appreciated.

Thanks