GRAND RAPIDS — A Minnesota angler landed an unusual trophy when he reeled in a shark jawbone while fishing on the Mississippi River.

Joe Piskel, of Grand Rapids, caught the jawbone near the town over the weekend. He and his son, Joey, brought it to a Department of Natural Resources office, where a fisheries biologist identified it as being from a sand tiger shark. That’s a salt water species that can’t survive in fresh water.

The Minneapolis Star Tribune reports that DNR officials said the jawbone didn’t appear to be a tourist trinket.

Its origins remain a mystery. Joey Piskel says the jawbone will be cleaned up and hung on the wall.