They're often valuable for vastly different reasons â like the World War II-era coins minted from atypical metals, or double-printed pennies â but each one is easy to miss if you're not paying attention. See also: Californian Couple Finds $10 Million Worth of Gold Coins in Tin Can.
A subsistence economy is a non-monetary economy which relies on natural resources to provide for basic needs, through hunting, gathering, and subsistence agriculture.
The Fourth World is an extension of the Three-World Model, used variably to refer to. Sub-populations socially excluded from global society; Hunter-gatherer, nomadic, pastoral, and some subsistence farming peoples living beyond the modern industrial norm.