I've never had a problem at all with peppermints from the store or florida eating anything but dead snails and aptasia, as well as mysis. Sounds like you had a camel shrimp. I'm not sure how well these guys are doing since I never see them. The only one I've seen since they went into the tank hangs out in the opening of my return from the sump after the lights go out. Its really weird seeing a tail end sticking out of a bulkhead.