Papua New Guinea police had earlier dismissed speculation that the 32kg object was "merely a dummy".
A police report drawing on analysis using an X-ray machine donated by Australia identifies the shell-shaped object as an undetonated artillery projectile.
After a scratchy win over Papua New Guinea, England need a miracle to stay alive in the Rugby League World Cup, and big questions need to be answered about the sport's future in its birthplace.
England’s Rugby League World Cup campaign is all but over despite victory over Papua New Guinea in their final group stage game
England edge towards a World Cup exit after their points chase against Papua New Guinea descends into a chaotic and error-strewn 34-12 victory that will almost certainly prove insufficient.
As many as eight million people have been affected by the cascading issues of food shortages, electricity loss and health clinic closures
Luka Rahan set off on a fishing trip with his cousin, but experienced issues with the boat's motor and, with no anchor on board, started to drift.
The deadly shootout with police follows days of gun violence in Kimbe, the capital of West New Britain province.
Technology
MPs in PNG to decide on ratifying a 2019 referendum in which Bougainvilleans voted overwhelmingly in favour of independence