After the late Italian artist Piero Manzoni canned 90 separate 30-gram specimens of his feces as art objects in 1961, the value for one tin soared to $75,000 in 1993, but in 1998 fetched only $28,000 at a Sotheby's auction in London. Forbes notes that even with the recent drop in value, at $1,000 per gram, it is still almost 100 times the price of gold.

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