The tank is running for about 1 year and I have the coral for about 10 months. I have other corals but nothing near by (and for sure nothing that can touch it). It started looking like that about 1 week ago. In the beginning it looked like it was shedding a skin layer (or something like that) ... and the colors faded in that area. now that fungus-like thing appeared.
I cannot remember if it started exactly like this or if it spread.
The tank is a 40 g and I have 4x24 T5 lights.
It seemed to be very happy ... even it was spreading to the rock underneath (see the right side)...