what does it mean if a coral turns brown?

[marie]

Or, if it was brown when you got it, then it could very well be.....a brown birdsnest.
Different lights can make corals appear to be a different colour then what they actually are and if the coral was in a tank with a lot of bluish light then it may well have appeared purple to some

[Ross]

What do you mean if a coral turns brown... I though thats how they all look... ...at least in my tank.