When you catch a white perch (drum fish) clean it and when you do cut down through the middle of the head, right behind their eyes are two flat rocks. They use these to make the so called drum sound! Take them out wash them and let them dry. When they dry look on the flat sides and tell me what you see...hint---it is a number, you tell me what you guys find. They also are known as good luck stones. An old timer showed this to me.