Sorry to hear about the carnage in your semp garden. Sounds to me that whatever took apart your semp was treating it like an artichoke: taking leaf after leaf apart until reaching the heart... Must be something pretty dextrous with their paws (like a squirrel). Here in NM, I have problems with birds sampling the semps or pulling the surrounding material out from around the semps for nesting material. I have to use a physical barrier to keep the animals from the semps.

I have seen evidence of munching this year also. A couple of the rosettes were left with only the outer leaves but have quickly regrown from the inside with new rosettes as the critter was gracious enough to leave enough of the middle intact. I am suspicious of the baby rabbit or the annoying striped gophers I've been seeing. The munching seems to have stopped now. They seemed to like my large green ones the best.
Deb

My gophers have dismembered them from underneath before.

The same thing has happened to one of mine too but I think it's a mole/vole or some such creature getting the root from underneath. I found a hole really close by.