The Schü-mine 42 (Shoe-mine), or Schützenmine 42, was a German manufactured anti-personnel mine used during World War II. It was a wooden box with a hinged lid hiding a 200-gram (7.1 oz) block of cast TNT and a spring mounted type detonator. A slot in the lid pressed down on the striker retaining pin, sufficient pressure on the lid caused the pin to move, releasing the striker which triggered the detonator.
The mine was cheap to produce and deployed in large numbers. It had only a tiny bit of metal in it. So that made it hard to detect. Essentially, dogs had to sniff them out. They were especially good at visiting casualties upon advancing infantry.