Biologists until earlier believed that while life requires various elements, including phosphorus that serves as the backbone for these nucleic acids that make up life's genetic material. Little did we know that arsenic that is placed very closely near phosphorous in the periodic table can support life too.
Arsenic is widely considered a sort of poison and cannot support life in any form. But scientist Felisa Wolfe-Simon decided to prove otherwise when she discovered the bacteria in California's Mono Lake, decided to grow it using sugars and vitamins and found out that the bacteria survived even without the presence of phosphorous.
"Organisms utilizing such 'weird life' biochemical pathways may have supported a 'shadow biosphere' at the time of the origin and early evolution of life on Earth or on other planets. Such organisms may even persist on Earth today, undetected, in unusual niches", says Felisa.
In a paper she co-authored called 'Did Nature Also Choose Arsenic?', she writes "we hypothesize that ancient biochemical systems, analogous to but distinct from those known today, could have utilized arsenate in the equivalent biological role as phosphate."