Cave pearl
（重定向自Cave pearls）
![A nest of cave pearls in Carlsbad Caverns, New Mexico](/Images/godic/202501/03/Cave_Pearls1832.JPG")
A cave pearl is a small, usually spherical, speleothem (cave formation) found in limestone caves. Cave pearls are formed by a concretion of calcium salts that form concentric layers around a nucleus. Exposure to moving water polishes the surface of cave pearls, making them glossy; if exposed to the air, cave pearls can degrade and appear rough.