Morgan waved a hand idly. "And how do you know someone hasn't dug it up, as soon as you look away? Even if you set someone to watch the spot constantly and reported back to you, how could you be absolutely certain they were telling the truth? Even if you watched the spot yourself, slept right on top of it so no one could disturb it, how could you know -- absolutely, positively know -- that someone hadn't very quietly tunneled up beneath it and removed it without disturbing the surface?"