GRAND RAPIDS, Minn. - The jawbone of a sand tiger shark that was snagged by a fisherman over the weekend in the Mississippi River has DNR officials scratching their heads.

The fisherman brought the jawbone to the DNR offices Monday morning to find out exactly what it was that he pulled from the mighty Mississippi near Highway 6, just west of Grand Rapids.

He posted the photo on Facebook, where he said there was still "flesh" on the jawline when he reeled it in, which made him think it couldn't have been decoration.

Fisheries biologists at the DNR identified the bones as that of a sand tiger shark, a salt water species that could not possibly survive in Minnesota waters.

The jawbone measured about 9-10 inches across.

The DNR said once identified, they returned the jawbone to the fisherman.