What is this ?

[k2damax]

Okay so I recently started a saltwater tank on sunday then today when i was adding some extra water I noticed that one of my dead corals ( it looks like this http://www.fws.gov/news/images/coral2.jpg ) started having some red stuff on it does anybody know what it is ? Oh yeah and I have some dead live rock in there idk if it will ever come back alive and I also have about 5 pounds of live sand that I got from Robert.

Thanks,
Kevin