The One-Star Earthling Dragonball is one of the Earthling Dragonballs.
Started cracked in Dragonball Xz.
After the Dragonball was restored, dark TRUNKS used it with the others to summon Shenron.
Scattered across Earth somewhere.
Due to their overuse, the negative wish energy within the Earthling Dragonballs caused the One-Star Earthling Dragonball to crack, releasing the Shadow Dragon, Syn Shenron.
The Shadow Dragon of the Cracked One-Star Earthling Dragonball. He was born from Popo's wish to revive everyone on Namek that was killed by Frieza and his soldiers, which also brought Porunga back to life.