GFAJ-1 burst onto the scene last December, with NASA proclaiming it held major implications for astrobiology. The microbe lives in a highly alkaline, hyper-saline and arsenic-laden eastern California lake called Mono Lake. Wolfe-Simon and research colleagues took it into the lab and simulated the lake environment, then diluted the natural phosphorus. Wolfe-Simon hypothesized that arsenic, typically toxic to life, could stand as a proxy for phosphorus, itself one of the six main ingredients necessary for life. The elements are similar in atomic structure, and there are a couple other examples of chemical substitution elsewhere in the kingdoms of life. After several rounds of experiments, and using several types of molecular analysis, Wolfe-Simon et al said the microbe successfully substituted arsenic for phosphorus and not only survived, but thrived.