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.
As noted throughout the above discussion of societal development, changes in the social structure of a society - in this case the primary means of subsistence - also affect other aspects of society. For instance, as hunters and gatherers make the transition into pastoralism and horticulture, they also develop a surplus in food stuffs.