I have a toadstool that I have had for about three years, it has grown to almost a foot in diameter and recently (about a month and a half ago) dropped about 10 pieces. Over Christmas it started shedding which is normal it does it about ever six months in my tank. But now after the shedding it has started turning white and bleaching. Im not sure what has caused this. My metal halide light was about a year and 3 months old. Could this be the problem?