Everyone else is probably scratching their head like me. What color was it before this? If I had to guess from the pictures, I would guess either brown slime disease, or the "speckels" are cyno or algae forming over parts that have died. Did you dip it before you put it in your tank? A little more information would be helpful too, like how long have you had it, what kind of lights you have it under, what your alk and other parameters are? It really hard to tell just from the picture.
Stephen