Gob shields are protective devices used in mining, particularly in coal mining. They are designed to prevent the collapse of mine walls and to protect miners from falling debris. Gob shields are typically made from sturdy materials and are placed in areas where the mine has been excavated but is not actively being worked. These shields help maintain the stability of the mine by supporting the surrounding rock and preventing cave-ins. They are an essential safety feature in underground mining operations, ensuring that miners can work in a safer environment while extracting resources like coal.