In 1653, Spanish explorers found the ruins of what appeared to be a Mesoamerican step pyramid in what is modern South Carolina. Though the site was far beyond the borders of any known American indigenous populations, it was also of a smaller size than existing Mesoamerican structures, and bore an unrecognized form of glyphic decoration. Local natives were familiar with the structure but knew nothing about it.
The Spaniards sought to disassemble the building as a heathen relic and did so, brick by brick, salvaging the materials to construct their own nearby settlement.
Deconstruction halted, however, when one brick was uncovered at the core of the structure, carved entirely of black glass. The stone, approximately two feet by three, was impossible to move or even budge by any man or animal.
Attempts were made to dig the stone out from beneath, but excavation revealed that it extended indefinitely into the earth. In frustration, the captain of the explorers fired a glancing blow off of the surface of the stone.
The obsidian block was undamaged, but moments after the blow had struck, it silently retracted downwards, sliding downward into a hole that quickly collapsed inward on itself, burying the retreating obsidian column.
The Spaniards interpreted this as an evil omen and abandoned the site, never to return.