Common name for that type of branching growth form would be a staghorn coral.
Can't really make a sure ID without a closer pic, but A. formosa would be a good guess.
my uncle and i bought a couple nice sized frags from that exact one you see in the pic. it was green when fragged, when we got home to put it in the tank it was a tannnish color, i hope that doesnt mean it is dead?
what kind of lkighting was it under b4 and what is it under now??
changes in color often times will stress a coral and make it brown out... given time it should color back up