In September 2021 I visited the
Besser Museum at Alpena, Michigan, USA. They had a large exhibit on Native American
artifacts found in Michigan. One that caught me attention was labeled "petoskey stone pop-eye", see picture above. It is a native American
bird stone made shaped from a
Hexagonaria coral fossil. They also have on display a copper bird stone identified as the only one known. The museum has an impressive collection of copper artifacts created by native American peoples of Michigan.
The Besser Museum for Northwest Michigan was named for Jesse Besser
(1882-1970) who perfected and produced machines that create these
famous concrete blocks. Out in the yard is a huge boulder sized Hexagonaria (Gürich,
1896) coral fossil (from Devonian Period). They also have
areas where you can search for and keep fossils from material dumped
there from local quarry.