I had a Dino issue for 3 months in my frag tank, one entire Zoa colony was closed the entire time ( Dino's do that >:(. )
But after they went away the zoas ALL opened back up, a bit lack luster for color but that's coming back as well.

But in regards to your first post
Something to watch for is Astraea star fish ( the wee tiny ones)

Some eat zoas, some don't.
I have both, most will completely ignore them, while others go right to them and start chomping down on them.

I've had a colony of cherry bombs not open for 6 months !
My sunny d's looked like that but I find sunny d's are tough though
Also lost a coral in my sand bed three months later found it doing my monthly sand bed stir :) all my zoas are happy now !

Talked to Denny at concepts and we figured it out

GFO my phosphates where crazy
And a better salt because I refuse to dose :)