25 Minutes in a reference to the variations magnetic globe indicates situationof preDeep Hot Biosphere geology reliance on a magnetic core being powerful enough to affect the 20 or so miles of crust insulation and become a field on the surface of the earth reliable for rudementary navigation.
It should allow or pause to ponder.
Antikythera Mechanism V2: A Modernized Reproduction
This thing would have benn a machine to navigate with sited likely on each sailing vessel of the day
