I have 3 Peppered Corydoras in my tank with a sand substrate. They're pretty small at the moment so I haven't seen them dig into the sand too deeply yet. My concern is that I have 2 pieces of driftwood that was purchased at the store that are attached to pieces of slate to hold them down I guess, some of the edges are just below the sands surface. While they dig, will they scratch/damage themselves while they're digging? Should I uncover as much as I can so that they can see them? Or do they just figure this out on their own?