They are formed when a small deposit of calcite lodges around a small grain of sand or minute rock fragment. During the period of growth they are suspended on a thin film of the water's surface tension, which allows them to rotate, forming perfect spheres. After they accumulate enough weight, they sink to the bottom of the pool. The running water will continue to agitate them until their weight makes them finally adhere to the bottom. The water helps them to keep their luster.
Most cave pearls are smaller than marbles, but some have grown to be the size of a softball.
Cave pearls are of no value when they are taken from their natural environment. If they are taken from the cave, they dry out and turn to powder. They are called cave pearls because they look like smooth gray or white pearls made by oysters. The name may, also, reflect the similarity of their formation to that of an oyster creating a real pearl. Dogtooth Spur Dogtooth spur are angular crystals that grow to be four or five inches long .