Perhaps its only in imagination that things can just randomly swish into existence and grow very complex, given enough time. The thing is, there isn’t enough time.
Sheldon: My best guess is that he has found something organically simple such as polycyclic aromatic hydrocarbons (PAH), if only because 3.5 billion years is a long time for organics to survive, and PAHs are the sort of keratonized (turned into keragen) that is stable.
This doesn’t leave a lot of time for Darwinian evolution (natural selection acting on random mutation). Not nearly enough, in fact.