VIENNA (AP) — Austrian police got a shock when they opened a backpack to find a live grenade shell inside.

State broadcaster ORF said Tuesday the World War II relic was found washed up on the shore of a lake northeast of Salzburg on Monday by a high school student.

ORF says the unidentified 16-year old did not recognize the danger, slipped the “rusty metal object” into his backpack and marched to the nearest police station.

Experts defused the shell. And the student was told to leave such objects alone in the future.

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