Sedimentary Rock Formation with Interesting Relief
North America, Eastern United States, Pennsylvania
Dimensions: 11" x 6 1/2" x 6 1/2"

The stone has a natural, weathered appearance with a distinct, deep inset impression. It is possible that this is a fossil impression, or a relief made by a different mineral formation from this limestone matrix. Due to the smoothing caused by erosion (and, I assume, river/lake water waves) I am unable to tell what made the initial impression. It is possible that this is a carved object, with the round hole and perfect symentry. But, from images, I am unable to tell.

While I do not believe this example has a high resale market; it is a unique formation. And, with your personal history of the example, it could make an excellent "Gongshi" example. "Gongshi", or Scholar's stone/rock is a "Nature-as-art" meditation stone that is used for counter or desk displays.

For more information on this example, an in-person consultation with a regional Natural History Museum or Geological Studies Department with a University is suggested. You could reach out to your local library reference desk for help in creating that appointment. Sometimes, these organizations hold rock and mineral shows and have free assessment appointments at those times. If it is discovered to be man made, the value with increase significantly. However, as a cultural artifact; it may not be legal to sell on the open market. It could be something you could donate to a museum or university.