Here's what Bob Fenner says about Heliofungia/long tentacle plate coral on wetwebmedia:
"Helio/Long tentacle plate corals rarely fare well for any length of time... especially if not placed on soft/fine sand substrates. "
As revsgirl pointed out earlier, daughter colonies, called anthocauli, form on a seemingly dead skelton of a parent coral. I bought daughter colonies of a fungia (the short tentacle plate coral) from a friend a couple of years ago. I gave away a number of the daughter colonies as they grew larger, but new ones seem to keep coming off of the tiny remainder of the parent's skelton.
By the way, Trachyphilia (Open brain coral) can also reproduce the same way.
Rising from the dead... kinda spooky, ain't it?