It's true that if life exists on other planets, it may not look exactly like life here. But it's also true that there are a small number of elements in the peri

It's true that if life exists on other planets, it may not look exactly like life here. But it's also true that there are a small number of elements in the periodic table, and only so many of those are even relatively common in the universe, and only so many of those are useful for reactions, etc, etc. The things that life on our planet use seem to be some of the most obvious candidates to use, if not the most obvious, so if life exists on other planets, it would be surprising if the things that we use are unique or even uncommon across the universe.