Try a freshwater dip and see what comes off.

There are so many possible culprits that the only way to tell would be to see what comes off in a dip - be it nudis, spiders, etc.

There are also some pathogens that obviously won't be determined by a freshwater dip. I would peruse the zoanthid forum on RC and maybe post there just for the sake of getting a more focused audience.

Dips will not get eggs, I think the only way to get the eggs is to manually remove them.

I cant see any eggs or nudis tho. The 2 other groups of zoanthids that had eggs were removed from the tank. They kind of look like they do when they expel their waste after I target feed them, but way worse. Ill just keep my eye on them and possibly dip them later tonight if they dont look better.

Dip