The discovery of the first known microorganism on Earth to thrive on the toxic chemical arsenic will help expand scientists’ understanding of the definition of life, said the head of the Vatican Observatory.

“It’s clear that if we are searching for life forms in the universe, we have to at least know what to look for: that is, to define what a living being is,” said Jesuit Father Jose Funes.

The recent discovery of a life form based on a completely different chemistry “will surely contribute to expanding our conceptual horizons on the subject” of what could be life and living matter, he said in an article in the Vatican newspaper, L’Osservatore Romano, Dec. 4.

A team of astrobiology researchers — funded by NASA — recently discovered a microbe strain, called GFAJ-1, in California’s Mono Lake, which has unusually high levels of salinity, alkalinity and arsenic.