because they depend on camoflouge, they can change colors quite a bit. all have the ability to make the front half much darker and the back half much lighter. mine sometimes is a light creme color on its back half, and a dark brown/purple on the front half. i have lots of dark LR with lots of coralline, and so my LMB is always a dark grey/brown, with a purpley tint (especially the eyes are a dark purple). Before I added all the LR and the tank was much lighter in color, the LMB was always a light grey/biege. I think that's part of what makes it such a cool fish, you never know what color it will be.
