u/rootsoflove

Hello, I have no background in geology but I saw several of these very round holes in the creek bed that ranged between about 2 feet to upwards of 10 feet in diameter—it fascinated me and I want to understand how this occurs, thank you! (My [certainly incorrect] guess is that there was some sort of differential erosion because a big rock was there that eroded faster than the surrounding stone?)

I had to lighten the picture up—I could not for the life of me get a well lit picture. I dug this out of my yard and did not get much help on r/whatisthisrock (if anyone knows what this mineral/rock combo could be, that would also be nice!)