A man from Makkum, Holland has kept old World War II hand grenades on his mantelpieces and used them as house ornaments without realizing they were dangerous.

Heimen van der Wal, said he discovered the grenades while he was playing in the woods near Arnhem, Holland as a child. He said he kept the grenades on his mantelpiece for decades.

His wife Marjan told the Antwerp Gazette, "We though they were harmless. Our children have even played with them."

Van der Wal moved the grenades to a barn a few years ago. Last week, he showed them to a friend who immediately realized the danger.

He adds, "He was shocked and told us to alert the army's bomb disposal unit, because the grenades were highly explosive."

A spokesman for the army said the family had been very lucky the grenades did not explode.

He said one of the pins of the vintage grenades was so rusty, that any sudden movement could have caused an explosion.