The hair-made heart (assumption).

Wet.
Thin.
Long enough.
Creation after death.
Unknown source.
Logical source: Human head.
Irrational sources: Human Ear. Human Nose. Human Arm. Human Leg. Human Genitals.

Clues for other sources: Horse tail. Extended snake tongue. Wire, sad due to its inability to achieve rebirth as hair.


Thanks to Konstantina for sending me the heart.