ID please

[tharkema]

Trying to identify this rapidly spreading saucer and cup shaped object. Two pictures are included one of the outside and one of the inside. It is brittle and breaks up easily like a potato chip. It starts off deep red in color and as it gets older seems to go to a faint yellow. I would like to get this ID'd as I am moving all my live rock to a new tank and want to see if this is helpful in any way or if I should be looking at getting rid of it (and the steps to).

Outside


Inside