The two sisters were walking home when they spotted a metal orb about the size of a softball. They didn’t know what it was when they picked it up, but they figured that scrap metal buyers who make the rounds where they live in northwestern Syria might pay about 30 cents for it.

It was a live cluster bomblet.

“It was gray. It was this big,” one of the sisters, Duaa, 10, said recently, stretching the fingers on her left hand as wide as she could. She recalled how her sister Rawa’a, 11, then handed her the bomb while she was holding their seven-month-old brother, Mitib, on her hip. A second later, it exploded, shattering Duaa’s right hand.

Rawa’a lost her left eye, and Mitib’s cheeks still bear scars from the explosion.

Syria’s 12-year conflict — now largely at a stalemate — has wrought widespread destruction and killed more than 500,000 people while forcing millions more to flee their homes. And like other modern conflicts, it has left a deadly legacy of unexploded artillery shells, mines and other munitions on farmland, roadsides and in buildings, posing an indiscriminate threat to lives long after the fighting subsides.