I actually got them from wal-mart. they're the really light plastic ones, so he moves them around a lot, often bringing his cool hide over to the warm side, so I think that he believes that he's a hermit crab. I just cut a hole out of the plastic, then used a lighter to melt the sides to soften them up. If I had to do the while thing over again, I would probably get the heavier terra cotta planter bottoms so they wouldn't move around as much.