You’d sequence this organism. If it came from earth you could tell. People would have either sequenced it already or a distant relative species where you could

You’d sequence this organism. If it came from earth you could tell. People would have either sequenced it already or a distant relative species where you could compare sequence divergence and when they shared a last common ancestor. Convergent evolution might lead to similar phenotypes but the actual sequence of genes involved is only going to be similar if those genes shared an evolutionary history.