<http://schema.org/alternativeHeadline>
"Scientists aren't ruling out the potential proof of life in a meteorite from Mars, but acknowledge they need an uncontaminated sample for Mars itself to be sure."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/space/stories/odd-tunnels-spheres-revive-questions-about-ancient-martian-life>