
Ankh
The Ankh is the ancient Egyptian symbol known as the key to life.
In Logan's Run, it is used by the runner underground as a covert indicator of membership. When Logan and Jessica reached "the last gate," where Jessica, attempting to remove the necklace bearing hers, accidentally lost it instead, the ankh proved to be the key to that gate. They were able to get through only because Logan still retained the key that he had taken from a runner he and Francis had terminated. His use of that key enabled them to get through, but Francis retrieved the key Jessica had lost and was able to follow Logan and Jessica.