melting zoa's

so I bought a zoa frag that's been at my lfs closed up for a few weeks. ive been waiting for him to open up to see what he looks like but no luck. so I bought it today because I noticed a few were starting to melt with at least a good 20-30 heads that still looked alive and figured its either now or never (ive had good luck with recovering very irritated zoa's and them turning out to be colorful and cool looking). brought it home cleaned it up like I always do with any frag I get from my lfs. had a flat worm inside the rock, a weird bug lookin thing that was probably predatory on zoa's and a weird lookin transparent white catapillar lookin guy. not so sure what the bugs on em were, but their gone now. I figured since these zoa's were so irritated I wouldn't take any chances and broke away most of the rock leaving the zoa's attached to the 'outter skin' of the rock and just kindve hollowed it out.



so my question is can zoa's recover from the point of melting? and if not at what point should I remove the few that are melting and how?