A Science article and subsequent LessWrong post discuss the potential existential threat of artificially created "mirror life,"  specifically mirror bacteria. This hypothetical life form, possessing opposite chirality from Earth life, could evade our immune systems and potentially cause a catastrophic pandemic. The authors advocate for a precautionary principle, urging against research aiming to create mirror life due to the immense potential damage and lack of significant benefit. While the threat is currently distant,  proactive measures, including research into detection and countermeasures, are recommended to mitigate future risks. Debate within the comments section focuses on the likelihood and severity of this threat.