Glendive Mt was once covered by the shallow western interior seaway about 75 million years ago. It's amazing that you can go seashell hunting right here in Montana, even though the closest sea is 1000 miles away. Ammonites and baculites are an extinct cephalopods with beautiful shells that are quite common in the Pierre Shale formation. It's fun to look at these ancient sea beds and best of all they are perfectly legal to take for a souvenir. And who knows.....it's certainly possible to find a Mosasaur that would surely get your name in the paper. We would be going on public land outside Makoshika Park.