A suspicious metallic object left in a staff bathroom at Tukes Valley Middle School prompted an evacuation of the middle and primary school this morning. The object, described as being no bigger than a pack of cigarettes and having a circuit board, was found in a staff bathroom which requires a key to access, said Battle Ground Public Schools spokesman Gregg Herrington. Students were evacuated from the middle school at 8:20 a.m., 10 minutes after classes began. Buses en route to the primary schools were notified of the evacuation and staged at an off-campus site.Police responded and determined the device was harmless. Students returned to school by 9:30 a.m. The feeling, Herrington said, was that the object was left as a prank. It is unknown if a student or staff member is responsible. “That was definitely what the feeling was, but I don’t think the prank was supposed to go that far,” he said. Either way, he said, “nobody is happy about it.”Herrington said school administrators are investigating the incident and are seeking to discipline the person responsible.