The Urim and Thummim are ancient objects mentioned in the Bible, specifically in the context of the Israelite priesthood. They were used by the high priest to seek divine guidance and make decisions, often in matters of national importance. The exact nature of these objects is unclear, but they are believed to have been stones or lots that provided answers to questions posed to God. In the Book of Exodus, the Urim and Thummim are described as part of the high priest's garments, specifically the breastplate. They symbolize the connection between God and the leaders of Israel, serving as a means to discern God's will in critical situations.