I had been using puppy pads and when I added the wood pellets I left the puppy pads underneath! Big mistake cuz they keep scratching and pulling up pieces of them.
What they do is tear off a small part of it and take off with it like it is a treasure but you are right about sometimes they eat things they shouldn't. Every time I see some of it exposed I try and take it out but that has been rather difficult with the heavy pellets on top. I am going to give it a change of pellets and I will then get the puppy pads out completely. When they sdtart the scratching they can then tear things into small pieces and eat it which is probably not good at all!