"the place was littered with Bouncing Betties"

Bouncing Betty
Creative Commons Attribution Share AlikeBouncing Betty - Credit: Warinhari, Wikimedia
A Bouncing Bettie, also known as the German S-mine, is a special mine which, when triggered, has a delay of 1-2 seconds then shoots up into the air and explodes, firing hundreds of steel balls in all directions.

The S-mine was designed to disable whole squads. It was developed by German forces during World War II. There were two types: the SMi-35 and the SMi-44.