If Earth hosted a technological civilization four hundred million years ago, whether native or interstellar colony, how would we know? Buildings and works would be ground to dust. Despite the popular imagination, the chances of getting fossilized are astronomical¹ and the fossil “record” is a stick drawing at best.
We might draw inferences from certain unlikely isotopic imbalances in minerals, and we do indeed see hints of these. Strange items in coal seams have been found, but none certainly technological—until The Artifact. About the size of a bar of soap, made of a polymer halfway between fullerene and diamond it bore unmistakable symbols, and offered glimpses beneath its impermeable surface of apparent circuitry. The five largest symbols incised—actually worked into the structure of the macromolecule—on the surface resembled letters, rendered in current version of unicode² as ɧɸƙɨɒ. Conspiracy theories abound in regard to whether other deep-time encounters with this script have influenced human language and culture.
¹ well, palaeontological.
² relax, work on adding Elder runes to unicode is well underway.

Deborah Pickett
Als Antwort auf Kit Bashir • • •Kit Bashir
Als Antwort auf Deborah Pickett • • •