Here is an interesting idea from Quanta magazine.
In searching for extraterrestrial life, would we even recognize it when we see it? Life might have a completely different chemistry on other worlds.
" In 2021, a team led by Lee Cronin of the University of Glasgow in Scotland and Sara Walker of Arizona State University proposed a very general way to identify molecules made by living systems — even those using unfamiliar chemistries. Their method, they said, simply assumes that alien life forms will produce molecules with a chemical complexity similar to that of life on Earth."
https://www.quantamagazine.org/a-new-theory-for-the-assembly-of-life-in-the-universe-20230504/
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