Nice, I have one growing off the side of a Lobophyllia, the skeleton is about the size of a dime and the flesh is about the size of a silver dollar. It's been growing slowly for a couple of months and has yet to fall off.
Yours is much more colorful then mine. Mine has a purple mouth with a dark brown/tan flesh. I have thought about cutting it off, but I don't want to risk damaging the stem it is growing from incase it keeps kicking out more fungia.