A child in a boat was shown by the Prophet Elijah the stones of carbuncles on the condition that he would show them to R. Joshua b. Levi in Lud. He did so and three miles distance from Lud he dropped them into a cavern and they disappeared.
The Boy in the Boat Who Was Shown the Stones of Eden
Bava Batra 75a; Gaster, Exempla No. 202