Mars Surface

At the Johnson space center lab, some fascinating shapes have been found in the Martian meteorite ALH84001. Some scientists propose that these geometric shapes could be fossilized microbes extant on Mars before the meteorite was blasted into space by a meteor strike and sent on a 15 million-year voyage to Earth. However, an exclusively inorganic origin for the shapes has also been proposed.
Small quantities of methane and formaldehyde recently detected by Mars orbiters are both claimed to be hints for life, as these chemical compounds would quickly break down in the Martian atmosphere. It is remotely possible that these compounds may instead be replenished by volcanic or geological means such as serpentinization.