"We followed the map as best we could, periodically checking our bearings using the chronograph and the sextants that the seer had given us. Eventually we found the deserted location that corresponded to the coordinates on the rapidly disintegrating map. And we began digging...
"We started a trench that went down about fifteen feet into the baking sand and headed due South. After a few hours our spades rang with the sound of steel on stone and as it did so the group gathered round to see what we had hit. Some hand digging revealed a dark black stone that had been carved with a strange texture on it's surface like a series of overlapping layers of petrified tendrils frozen for perhaps a thousand years. It looked and felt utterly alien, and yet our goal lay in the centre of this forbidding artefact.
Captain Blackthorn grimaced against the salt air that sandblasted his face. His men were weary, his ship was falling apart and the hold was replete with treasures beyond counting. It was time to head home and enjoy the bounty that years at sea had brought them. As he braced himself against the pressing squall he considered the conundrum of converting said bounty into a transferable asset that could easily be spent without arousing suspicion of the local militia or the jealousy of rival pirates. If only large amounts of wealth could be represented on something as light and unobtrusive as a piece of paper. But then Blackthorn had a idea:
"I know what we'll do! We'll bury it!…"
The Yugzhee, or "hedgehog-people", guard a great, secret treasure inside their giant burrowed lair. The mysterious Wall of Keys, a 12'x10', foot-thick, cold-iron, "wall", upon which, on iron hooks, hang 100 ornate iron keys of all shapes and sizes. Each key opens some heretofore un-openable barrier, door, or gate, in the particular game world of choice.
The PCs have come upon a great boon, except for the fact that the keys cease to function properly if separated from the iron wall for more than a few minutes. Higher level characters will be able to figure out how to take the wall "with them" via magic. Lower level characters will have to get creative.