All organisms contain genetic material. Be it DNA or RNA, both of them have a fixed pentose group (deoxyribose and ribose). Also they contain the same types of nitrogenous bases, Adenine, Thymine(or Uracil), Guanine, Cytosine.
What makes ribose and these notrogenous bases so good that among all the molecules in our pre-historic chemical pool, these selective compounds made our genetic material.

Why don't different organisms have different bases/sugars? I understand that we all have a common evolutionary ancestor so the the genetic material will be similar. But mutation is possible, so why is that there are no nucleic acids found naturally that are made of different bases or sugars? Just for example, if we had a hexose like glucose for the sugar instead of pentose..