you mean phosphorus?
Heck I dont know. I'm old and dont remember alot of that stuff. ;D
I was meaning more of an organism using some other material besides what our known life uses.
Take humans for instance. We breath air(obviously) 21% O2 79% N respectively. Why does another organism be required to use that. My main point back then was they were using a closed mind. What was proven fact years ago changes over time with technology and more research. Lets just hope its non bias research.
Like the whole Alien life form deal. i dont know if there is or not. Is it a possibility, sure, do I believe in them. Na, not till I meet one. ;D Why does a life form have to have the same gases we use to survive. The very life for could be programed to use the abundant gases on that planet to metabolize as we do with our abundant gases.