Kona Dolomite dated to over 2 billion years old. Thought to be a cyanobacteria colony (stromatolite). Found in the Kona Hills of Marquette County, Michigan. These early oxygen producers paved the way for more advanced lifeforms of the future.
This specimen has finally been polished and buffed (thanks Kenny) after I cut it with the diamond saw and smoothed it with high grit sandpaper. It is destine for the education collection of a local public institution.