I found these rocks at the beach a few days ago. I couldn’t for the life of me figure out what made such perfectly round holes in the rocks. I looked all over the internet, not really knowing what to search for, since I had no clue what made these. I found a bunch of Etsy shops selling these rocks that people had found, but then I found this post on someone’s blog, and the commenters had some good theories, but no one there knew exactly what happened either, and why the holes were so smooth and perfectly round.
Then my cousin and her husband came to visit, and I showed them my rocks. This particular cousin and her husband have a vast wealth of knowledge about all things nature/earth/plants/animals. They are very “earthy” type people. Anyway, my cousin said her friend calls them “fairy rocks” – supposedly they are good luck. Her husband said they are made when little pebbles get stuck in the rocks. Then the waves beat down on the pebbles, drilling holes through the rocks. He mentioned that most of the rocks this happens to are hardened clay/mud rocks, which will crack and fall apart if they dry out. That happened to a few of my stones, but some of them I believe are rocks.
You can see a pebble stuck in one of the holes on the rock at the very bottom of the picture. It was just amazing how smooth and round the holes were! I guess the pebbles act like a drill bit. Amazing!