Fairy Stone

Fairy stones, sometimes known as Goddess stones or Menilite Opal, are unusual minerals composed of calcium carbonate and clay. The “disc”, which is common slang to describe their structure, can sometimes be formed over small pebbles and even fossils. You’ll most likely find them in a grey or off-white color, but they can also be seen as tan, beige, and brown. 

Fun fact: many native cultures see fairy stones as a symbol of good luck!