Introduction to Pearl Hall: The third hall is the "Pearl Hall". There are also many marks on the roof of the hall. Some of them are rock fissures filled with calcite, and many are stone carvings from the Han Dynasty in China. Some of the characters that are difficult to identify have been made into rubbings and sent to relevant departments for research. In addition to its important tourism value, Kaiyuan Cave also has precious archaeological value. The top wall of the cave is covered with snow-white pellets, which look very much like pearls, so it is called "Pearl Beach". The scientific name of the pellets is stony grape, and those that grow into coral-like shapes are called stony corals. The chemical composition is calcite and it is white. Its large distribution is also rare in other caves. It is one of the treasures of Kaiyuan Cave.