What property of amino acids is considered an incredibly potent chemical biosignature if observed in a highly biased state?

Answer

Homochirality

Life favors specific 'handedness' (chirality); if a sample shows a significant bias toward only L- or only D-amino acids, this homochirality implies a system capable of selection and replication.

What property of amino acids is considered an incredibly potent chemical biosignature if observed in a highly biased state?
sciencelifedetectionbiosignature