Relevant info first: This was found in Petoskey Michigan while looking for Petoskey stones. It was found in partially buried in sand. It is quite large and rather heavy. As pictured in picture 5, there is some sort of opening at the end? I can't get a very good picture of the inside, it's hard to get light where i need it and take a picture. the hole looks to maybe be about a 1/2 mm deep, and less than that wide. I took to reddit, albeit with less detailed photos and was told it was a straight shelled nautiloid cephalopod from the paleozoic, and that it was a brevicone, which I'm hoping someon