... A Berry Bowl of Martian Spherules . ... Credit: Mars Exploration Rover Mission , JPL , NASA Explanation: How were these unusual Martian spherules created? Thousands of unusual gray spherules , made of iron and rock but dubbed blueberries , were found embedded in and surrounding rocks near the landing site of the robot Opportunity rover on Mars . To help investigate their origin, Opportunity found a surface dubbed the Berry Bowl with an indentation that was rich in the Martian orbs . ...