What is Causing Damage to My Acropora?

A lot SPS will be a paler shade on the underside and in spots where they don't get much light. Is the light spot similar in color to the underside of the rest of it?

 

Yeah, pretty close. Maybe a little paler, but there is still good tissue coverage. And the spot the was damaged is filling in with new tissue. If you look at the first post in this thread, the pale part is right in the shade. The rock has been moved a bit and now it's being hit with light. Maybe that part is still adjusting?

 

It will take some time for the pale part to color up if it was shaded before.

 

Yeah, I just took another look this morning, and it's pretty much the same pale shade as the other areas that don't get light. With my tang dying yesterday, I think I was on high alert.

 

Most of the original damaged spot has healed up, but I found a new spot that has been attacked in a much harder to reach/see location. It's hard to describe. It's like a translucent, white - almost sponge-like in appearance. But it's difficult to rip away from the coral and rock. When you take it off, it's almost like pulling away a nest of spider's eggs. It has kind of a stringy, but tough texture. It appears to grow very, very slowly. When I removed it from the tank, it had kind of a fishy odor. Like smelling the inside of a clam or mussel. It doesn't appear to move around but rather grow on the coral. Very strange.