Your right, the box is a big rubbermaid box that I use for a humid hide. The top is locked down and a paver stone (brick) is on top so he can't remove the lid. I fill it with moist, not wet, mulch. Tegan also seems to like to shred up newspaper and pull it in there, not sure why? Nesting I suppose. They seem to like a tight fit, so it works perfect. I literally fill it with mulch and he burrows into it. They LOVE TO DIG! make sure you have a good 6-8" of mulch to allow for their burrowing pleasure on the cage floor too. They are really fun to watch when they are in the digging mode.