Arsenic sits right beneath phosphorus in the periodic table of the elements and shares many of its chemical properties. Indeed, that chemical closeness is what makes it toxic, Dr. Wolfe-Simon said, allowing it to slip easily into a cell’s machinery where it then gums things up, like bad oil in a car engine.
At a conference at Arizona State about alien life in 2006, however, Dr. [Felisa] Wolfe-Simon suggested that an organism that could cope with arsenic might actually have incorporated arsenic instead of phosphorus into its lifestyle. In a subsequent paper in The International Journal of Astrobiology, she and Ariel Anbar and Paul Davies, both of Arizona State University, predicted the existence of arsenic-loving life forms....
Reasoning that such organisms were more likely to be found in environments already rich in arsenic, Dr. Wolfe-Simon and her colleagues scooped up a test tube full of mud from Mono Lake, which is salty, alkaline and already heavy in arsenic, and gradually fed them more and more.
December 2, 2010
"It’s like if you or I morphed into fully functioning cyborgs after being thrown into a room of electronic scrap with nothing to eat."
The newly discovered arsenic-eating bacteria. But it's not really that weird: