Doran was gifted with a Soul-stone by the Auron tribe for showing them how to make fire after half their tribe had been stripped of magic and banished from the island of Auron. Doran carried the Soul-stone throughout his life, and it recorded his memories.
After Veritas took Doran's breath, his body crumbled, leaving behind his Soul-stone, among other objects.
The Sister of the South
Lief placed the Soul-stone among his silver flask at a grave they dedicated to him on the coast of The Finger. Touching the Soul-stone gave Lief a look into Doran's memories, and allowed him to learn the names of the seven remaining dragons of Deltora.