Originally Posted by The_Heretic

Actually, to get silicon based life requires that silicon consistently behaves like a nonmetal rather than a metal. Metaloids are those elements [seven of them, including two in the same periodic table colume as carbon, ergo exhibit similar chemical properties] that switch from acting as metals or nonmetals depending on conditions. The key is to get silicon- or germanium to behave as a nonmetal all the time.

However, even with biocarbon organisms [as opopsed to biosilicon, biogermanium, bionitrogen or biophosphorus] there's still an astounding range of variation possible based on differences in chemistry. Now because of other single celled organisms found two miles deep into the Earth's crust- living within solid rock no less, all of those are biocarbon, use the same aminoacids for their genetic code and have roughly the same metabolic pathways as many extremophiles found on the surface [Yellowstone hotsrpings] or in thermal vents at the ocean bottom. The key is what gasses organisms in this aquatic crustal void are exchanging and- in lieu of plantae; animalia; or fungae, what alternative biological classifications could manifest?