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

"Mirra 530 features the latest in pool cleaning technology and an easy-to-use design, bringing yet another state-of-the art solution to iRobot's line of home robots, " said Jeff Beck, chief operating officer at iRobot.

ENGADGET: iRobot flaunts the Mirra 530 pool cleaning robot, sends the Looj 330 abroad

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.

FORBES: Fulfilling The President's Green Dreams Through Private Competition