While exploring the Red Planet, NASA's Curiosity rover recorded increases and decreases of methane levels, which could suggest the existence of microbial life.

While exploring the surface of Mars, NASA's Curiosity rover observed an increase in methane levels lasting approximately two months over the course of a 20 month period.

Currently, scientists don't know what caused this, but it's possibly from methane producing microbes.

The findings do not show if living microbes are present, but do indicate there is chemical activity on the Red Planet, and may even be a sign there are conditions favorable to life.

On Earth, 95 percent of methane is produced by microbial organisms. It also can be created by volcanos or hydrothermal activity.

The source of it on Mars is currently unknown, but is theorized to come from underground pockets. How it got into these pockets, though, is also a mystery.

Two suggestions have been made. One could be biological either present or past activity, while the other has to do with a natural process that produces methane when water comes into contact with certain rocks.

Unfortunately, the current amount of gas is too low to analyze.

Scientists are hoping another spike in the methane level occurs. If it does, they'll be able to take samples of it to potentially to determine whether its source is biological or geological.