Dubbed Bumpy Boulder, the strange stone measuring just under a half-meter high was found by the robotic Spirit rover currently rolling across Mars.
Pits on the ragged rock are likely >vesicles and arise from hot gas bubbling out of hot rock ejected by an active Martian volcano.
Several similar rocks are visible near Bumpy Boulder that likely have a similar past.
The >above true-color image was taken about one month ago.
The >Spirit rover, now in its third year of operation on Mars, is weathering the low sunlight winter of Mar's northern hemisphere on a hillside slope in order to maximize the amount of absorbable >battery-refreshing sunlight.
