Exodus 16:13-15

That evening vast numbers of quail flew in and covered the camp. And the next morning the area around the camp was wet with dew. When the dew evaporated, a flaky substance as fine as frost blanketed the ground. The Israelites were puzzled when they saw it. “What is it?” they asked each other. They had no idea what it was. And Moses told them, “It is the food the LORD has given you to eat.