A protest of the Keystone XL pipeline last March along its proposed route near Bradshaw, Nebraska. NH/AP hide caption

itoggle caption NH/AP

A tasseled wobbegong shark (top) lies on the seafloor with the head of a brown-banded bamboo shark in its mouth on the fringing reef of Great Keppel Island on Australia's Great Barrier Reef in August 2011. Reuters/Landov hide caption

itoggle caption Reuters/Landov

Magellanic penguins strut their stuff on the rocky shoreline of Argentina's Punta Tombo, home to the largest colony of the birds in the world. Craig Lovell/Corbis hide caption

itoggle caption Craig Lovell/Corbis

Charles, Prince of Wales, smells before tasting some ice cream during a visit to Gloucestershire. Maybe he was sniffing for fat? Barry Batchelor/Getty Images hide caption

itoggle caption Barry Batchelor/Getty Images

Some men take testosterone hoping to boost energy and libido, or to build strength. But at what risk? iStockphoto hide caption

itoggle caption iStockphoto