You may have seen this picture before as it was part of a puzzle years ago. A Gelman engineer, Jack Wyman, designed it and while it was originally developed as a study in circles and squares, he said it could also be interpreted as an idealized membrane filter structure, a reference to Gelman products.
![source: imgur.com](https://imgproxy.geocaching.com/e9113d1a2a6563d5ce20ba005136926f6a5247b7?url=https%3A%2F%2Fi.imgur.com%2FFv3EIH6.jpg)
The difficulty rating is only due to the fact that it may take you some time to locate the container.