Answer:
Due to urease activity, bacteria are able to use urea as a sole nitrogen source and produce ammonia, which increases the pH in the proximal environment, causing Ca2+ and CO32- to precipitate as CaCO3.
That its not in the cell or that its just there or that you can't find it anywhere else but in the body outside the cell....
The nutrients in some soils could be toxic to microorganisms/fish in those ponds or lakes.
