NASA's announcement Thursday afternoon has shown that alien life might have been under scientists' noses all along. A press conference with a team of researchers revealed that alien life forms could exist in drastically different forms than previously thought.

Two years of study at Mono Lake near Yosemite National Park in California have yielded a type of bacteria that thrives on the toxic chemical arsenic. The elements necessary to support life on Earth are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. However, this discovery refutes the previously accepted idea that extraterrestrial life forms would be made out of these same DNA building blocks.

"We know that some microbes can breathe arsenic, but what we've found is a microbe doing something new – building parts of itself out of arsenic," said Felissa Wolfe-Simon, a NASA astrobiology research fellow and lead scientist on the study. "If something here on Earth can do something so unexpected, what else can life do that we haven't seen yet?"

The newfound microbe, called GFAJ-1, was cultivated in an environment with scarce amounts of phosphorus and generous helpings of arsenic. Even when phosphorus was taken out of the mix in favor of more arsenic, the being continued to thrive, which debunked the idea that arsenic was a hostile chemical. In fact, it helped GFAJ-1 grow.

"The idea of alternative biochemistries for life is common in science fiction," said Carl Pilcher, director of NASA's Astrobiology Institute at the Ames Research Center in California. "Until now a life form using arsenic as a building block was only theoretical, but now we know such life exists in Mono Lake."

NASA said Mono Lake was specifically chosen as the research site because it has a strange makeup that includes high concentration of arsenic as well as high levels of saility and alkalinity.

"The definition of life has just expanded," said Ed Weiler, associate administrator for NASA's Science Mission Directorate in Washington. "As we pursue our efforts to seek signs of life in the solar system, we have to think more broadly, more diversely, and consider life as we do not know it."

Details about the press conference were vague enough to cause wild speculation around the Web. When it announced the conference on Monday, NASA said it would "discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life," inciting bloggers' hopes that NASA had actually found E.T.

Though NASA said it's an important breakthrough, it's not the big announcement for which many were hoping. So while this finding means that life on Mars might exist in some form, for now, it's just the title of a David Bowie song.