Oh Greg, what a wonderful colony of Orostachys spinosa 'Minuta'.
I lost all of mine 3 types to slugs, before I was aware there was a problem. I now put slug bait down in Jan. and again some time in the spring. I realized that the slugs had been tasting other plants, like semps and sedum, but didn't seem to care for the taste and left them alone. But the Orostachys spinosa (all varieties) they absolutely loved and cleaned them all out overnight. I know it was them, as they were out there early in the morning finishing off the last morsels. And yet they don't go anywhere near the other species of Oros.
Turned out that was why I didn't have hostas either.
I will have to give spinos a try again now that I know the secret of keeping them.