• This refers to the biological state where certain organisms like the bristlecone pine and the jellyfish can live forever.
• These organisms can be killed by external causes like injuries caused by harmful predators, catastrophic changes in their environment and fatal diseases, but they do not get fatally affected by the ageing process like in the case of other organisms.
• They are considered to be biologically immortal as they can possibly live forever by endlessly replicating their dying cells. Some scientists, however, have argued that such resistance to ageing may decrease over time.

Source:TH