zoanthid assassin?

[JTaylor420]

hey guys not sure where to begin over the last few months my zoa colonies seem to disappear over night colonies ranged in size from 20-50 heads i am keeping an extremely close eye on the remaining colonies but i am clueless as to how this is happening. I have an sps dominated tank and water parameters have been perfect since the start of the tank inverts i have a peppermint, cleaner, fire and coral banded shrimp a purple lobster and various hermit crabs. could this be a nudibranch problem if so anyone have any ideas? Or is there hermits out there that eat zoa's that i'm unaware of any info would be appreciated. thanks