About eighty years ago, a band of seafaring pirates plundered other ships and coastal towns, stashing treasure chests here and there as pirates stereotypically do, and composing maps of the areas for their eventual retirement. These particular pirates were never defeated, and they did indeed use these maps to retire. One of the maps has been passed down two generations but the treasure was never recovered, due to the harsh nature of the coastal forest it is purported to be buried within.
The map is of simple design, inked on cloth. It shows a large, pyramidal shaped rock and a large free-standing tree. Directly between these two objects, X marks the spot.
After fighting through the forest, which is unsurprisingly inhabited by unfriendly creatures, the group finds the rock, and nearby, a large free-standing tree. Several hours and two broken shovels later, they find nothing. Grumblings begin that the map is a hoax.
It’s not a hoax. The tree they found is indeed large and free-standing, but it’s a red herring. It isn’t eighty years old, which the group had forgotten was the age of the map. The tree the map references is nothing but a rotted stump and a bit harder to find than the obvious tree.
In the "new" spot, the treasure (whatever it may be) is quickly discovered.