Comparing formations observed on Mars to an active geyser in northern Chile, Arizona State University researchers may have found new evidence that life once existed on Mars.

The researchers, using images of a plateau of layered rocks known as Home Plate captured by NASA’s Spirit rover during its third year on Mars, were able to compare observed silica deposits that they said look quite similar to the formations at hot spring and geyser locations in Chile. The formations are complex, according to a Tuesday report by Space, and would likely come as a result of both living and non-living organisms and events.

"Although fully abiotic processes are not ruled out for the Martian silica structures, they satisfy an a priori definition of potential biosignatures," the authors of the study wrote in their findings, published last week in the journal Nature Communications.

In other words, they can’t rule out non-living sources as being completely responsible for the formations on Mars. But what they saw indicates that they theoretically could have come at least in part from living sources.

The ASU researchers performed field work in Chile to explore the phenomenon. The specific location, El Tatio, has local conditions that are similar to what might be found on Mars, at least compared to other sites on Earth like Yellowstone National Park, where other geysers that create formations the researchers were studying are found.

Part of the earlier doubt expressed by the researchers comes from tough standards for asserting that anything on a different planet came from life.

"Because we can neither prove nor disprove a biological origin for the… structures at Home Plate, they constitute a potential bio signature," the researchers wrote.

The Spirit rover is no longer exploring Mars after getting stuck in soft soil in May 2009. The rover was eventually decommissioned completely in 2011 when NASA decided that its lack of mobility and harsh Martian conditions were too much to maintain. The ASU researchers suggest that a closer look at the Home Plate structures could help to better determine if there are signatures of life in them.