I Found Ultra-Pure Quantum Crystals in an Abandoned Mine in the Atacama Desert | Hacker News

A Hacker News post explores whether nonhuman intelligences could have built civilizations and disappeared with little trace.

It uses birds, theropods, and octopuses as examples of animals that might have evolved advanced societies.

The discussion echoes the Silurian Hypothesis: over millions of years, even technological civilizations may leave only faint archaeological evidence.

The main point is how hard it may be to detect long-vanished civilizations in the fossil record.