In August 1996 President Bill Clinton addressed the world about a 4.3 pound rock from Antarctica. This episode tells the full story of ALH 84001, an orthopyroxenite that crystallized on Mars about 4.091 billion years ago, dated by potassium-argon methods, and formed carbonate grains in water at a mild 18 degrees Celsius. The hosts explain how a meteor impact around 17 million years ago launched it off Mars through spallation without melting it, how it landed in the Allen Hills roughly 13,000 years ago, how Roberta Score found it on December 27, 1984, and how trapped gases matched the Martian atmosphere, with a 2005 study tracing it to Valles Marineris.

The episode then examines the four pillars of David McKay's 1996 claim: bacteria-like shapes 20 to 100 nanometers across, colony-like groupings, rectangular magnetite crystals thought to be m ...