The mortar was found near Shell City bridge. Written By: Staff reports | × The mortar was found Sunday, May 16, near Nimrod, Minn. (Photo courtesy Wadena County Sheriff's Office) Some treasure hunters had a find so unusual they just had to show it off Sunday, May 16, at the Nimrod Bar. A group was searching the area near Shell City bridge with metal detectors when they found an old mortar covered in rust. It appeared to be very old, but also looked like it could be live, according to a news release from the Wadena County Sheriff's Office. One of the individuals called the sheriff's office and shared that they were at the Nimrod Bar, in the city of Nimrod, with the mortar.