Investigators in Prince George's County, Maryland, later said the substance appeared to be an ordinary cleaning solution.

CNN: Subway checked for hazardous material; none found

Hazardous-materials technicians called to the station determined that the man had sprayed cleaning solution in the air.

CNN: Subway checked for hazardous material; none found

When Rubinstein got the pendant home in February, he dropped it into a jewelry cleaning solution, expecting it to disintegrate.

WSJ: Man hunting for pythons finds mysterious jewelry

In a single year, without any federal funding, the X Prize had identified a problem, incentivized a solution, and produced a more efficient and cheaper technology that more than quadrupled the industry standard for cleaning oil spills.

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