[stephc_int13]

Biological immortality seems to be a reality for some not-so-simple organisms, the immortal medusa (https://en.wikipedia.org/wiki/Turritopsis_dohrnii) and even lobsters.

Biological organisms already have an impressive capacity to repair themselves. They don't avoid death at the cellular level, they simply replace dying cells with new cells.

And this is the case for many if not most of our cells.

As long as they don't die all at the same time, a biological organism should be able to maintain this cycle of replacement forever.

It might even be something simple, like the telomere repair mechanism.