the.com/biosignature

means A measurable substance or pattern — a gas, mineral, or molecule — whose presence suggests biological activity, past or present.

from A modern scientific compound, stitched together from Greek 'bios' (life) and Latin 'signatura' (a mark or sign, from 'signare,' to seal or mark). The term itself is a 20th-century coinage, built as biology and astronomy began hunting together for life's traces — in ancient rocks, in alien atmospheres — needing a word for the telltale residue life leaves behind even when the living thing itself is long gone or light-years away.