system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is it possible that some animals are "immortal" and can only die from predation?
gpt
There are two ways that immortal animals have come to exist. The first one is that their telomeres don't decay. This leaves them for high risk of cancer and other genetic issues but they technically don't age. This is how lobsters do it. 

The second big one is that whenever they die they revert back to a infantile state and start over again. This is down by a couple breeds of jellyfish.