Themiscyran Throwing Necklace
From Jenny Everywhere Wiki
In Reality Z-25 31-H, Gwenna often wore a Themiscyran Throwing Necklace given to her by Jung-La as her Christmas present. Made of kirbium, this crescent-shaped necklace could be thrown as a weapon; it would hit its target and then usually return to the thrower’s hand. (COMIC: Situation on Earth-N)