vestige

jälki, jalanjälki The mark of the foot left on the earth; a track or footstep; a trace; a sign.
A faint mark or visible sign left by something which is lost, or has perished, or is no longer present; remains.

(ux)

Any person seeing such a condition could not help being frightened at the conditions found, and it seems to me that that fact should lead us to think that the appendix is a vestige or becoming so.

Now this paired organ of Jacobsen began in reptiles and is well developed in many mammals. But in man it is a vestige, often disappearing altogether; and the two openings are closed.

This idea was confirmed by Scott, who performed a detailed comparative analysis of primate anatomy and demonstrated conclusively that the appendix is derived for some unidentified function and is not a vestige.