Will a dead coral raise nitrates?

Also, if a coral starts to die, is there chance of bringing it back? My LFS has one thats about half way dead, he said he'd give it to me to take home and maybe it'll live, is that true?
 
It's partly true. If you put a dying coral frag in an environment where it can live, it will. Each individual polyp is its own organism, so the dead polyps won't come back, but they may be replaced eventually as the coral grows.
 
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