the.com/vestige

The fading footprint of something that used to matter.

means A trace or remnant left behind after the thing itself is gone — a last visible bit of what once existed.

from From Latin vestigium, meaning 'footprint' or 'track' — the mark a foot leaves in the ground. The word walked into French and then English still carrying that sense of a trace left by something that has moved on, which is why 'vestige' still feels like standing in a footprint after the walker has vanished.

etymology
from Latin vestigium, meaning footprint or track
biology use
describes useless leftovers, like your appendix
implies
the function died, the structure stuck around
not
a relic you keep on purpose
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