Students show off the results of their trades. Caitlin Kenney/NPR hide caption

The hallucinogenic mushroom Amanita muscaria. Harvard biologist Donald Pfister claims that both people and reindeer ate the mushrooms. "Reindeers flying -- are they flying, or are your senses telling you they're flying because you're hallucinating?" he says. John Tann/flickr hide caption

Shell's Nanuq was built especially for oil spill response cleanup in the Arctic Ocean. It can store 12,000 barrels of recovered oil. The 300-foot vessel is docked at Dutch Harbor, Alaska, for the winter. Jeff Brady/NPR hide caption

Retired Army Sgt. Alexander Reyes (right), from Miami, responds to applause at Camp Liberty in Baghdad after sharing the story of how he was wounded by an IED in 2007. He is one of seven wounded veterans who recently returned to Iraq as part of Operation Proper Exit, a program aimed at helping soldiers heal from traumatic injuries. Deborah Amos/NPR hide caption

Jennifer Michaels recently interviewed her dad, Don, at StoryCorps in Bellefonte, Pa. StoryCorps hide caption