Alashan Ophthalmic Stone is a stromatolite fossil, which is a very rare prokaryotic fossil in the world. Ophthalmic stone was formed 300 million years ago and exists in high temperature and high pressure magma. It forms bubbles due to gas accumulation, and then it is filled with silicon dioxide and various trace elements, forming attractive eyes of different sizes.
Later, after the continental plate rose, the magmatic rock layer emerged from the earth's surface. After 8,000 to 6,543.8 billion years of weathering and rock mass separation, it finally formed the attractive eye stone you see today.