I had a beautiful Acan frag that I paid an arm and a leg for it, then I saw one of my peppermint shrimps over it one night but didn't care too much, after all peppermint shirmps were reef safe, rigtht? WRONG.
I was feeding my tank the following night and discovered the frag was gone, only the skeleton remained, all the tissue was gone.
I posed this in my local reefers forum and was quickly mocked by a ton of people. They burned me so bad it was the last time I posted anything there.
Now I feel vindicated.
Remove those little devils off your tank asap; they may be good Aiptasia eaters, but they do have an appetite for corals too.