They are roly poly or pill bugs and they are crustaceans. They molt and leave a little shell like skin. They generally only munch on dead plant material in damp places but I just found a group of them munching on my sempervivum roots on one of my plants. I used diatomaceous earth, mixed it into the soil and replanted the dozen or so that were around it. I had to amend the whole rock garden bed. They are doing fine now and the destruction has stopped. Some people dust their roots with it before planting. You can get diatomaceous earth at any Tractor Supply store and sometimes find it at Lowes. You can also get it online. It will kill insects around the house too. We put it around the outside of the house and puff it into the kitchen cabinets too. Haven't seen a bug in the house in years! Take precautions to not breath in the dust. Hope this helps!
