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Geology/Foissl or not?


fossil or not
fossil or not  

I’ve been collecting fossils and other interesting rocks from many states, and never have I seen anything like this. This was found in the thumb of MI, and it seems that most every time I go back I find more oddities like this. I would like to know what you think. Thanks for your time.

Hi Cora,
I'm sure you have a piece of Rugosa (Horn Coral).  At least you can see a part of it that has been exposed from the ground rock by erosion.  I'd expect to find that kind of fossil just where you did in Michigan.  It's probably from the Niagaran formation and is about 400 million years old or so.  It's a "solitary" coral and is shaped just like it's name.

Here are a few good pics.  There weren't any exactly like you specimen but theses give you a good idea of the fossil.  Note the ridges on them....

Pretty good descriptions;§ion=attach&attach

Near top of the page, good assemblage;

Hope this helps.


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C. Robert Reszka, Jr.


I can answer any general geology question (rocks, minerals, stratigraphy, geomorphology etc.). My expertise is in the geology of the Michigan Basin, PreCambrian, Paleozoic and Recent. I can answer questions concerning mining and petroleum exploration and production and the laws concerning those activities. I can also answer questions concerning stratigraphy of the Michigan Basin. I will also answer questions about mineral and rock collecting in the Basin. I won`t be able to answer many specific questions on hydrology, geophysics or geochemistry. I may be able to answer very general questions in those venues.


I have been working for the State of Michigan for 36 years as a Geologist and a Resource Analyst. I have experience with Subsurface Geology and Petroleum Geology, mining in Michigan, and Sand Dune Mining and Protection issues.

Michigan Basin Geological Society

Decade of North American Geology.
Bedrock Geology of Michigan

BS Wayne State University

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