From the Chicago Tribune:
Forty feet below the surface of Lake Michigan in Grand Traverse Bay, a mysterious pattern of stones can be seen rising from an otherwise sandy half-mile of lake floor.
Likely the stones are a natural feature. But the possibility they are not has piqued the interest of archeologists, native tribes and state officials since underwater archeologist Mark Holley found the site in 2007 during a survey of the lake bottom. Read more.