Fire bricks are specially made high temperature bricks for use in fireplaces, circulators, stoves, barbecue grills, furnaces and inserts. They are made from ceramic material and can take up to 2000 degrees. Since most modern ceramic cookers are good up to this temperature, clearly you can use fire bricks safely in a ceramic cooker. The bricks are sand colored and somewhat fragile. You can take two of them, grind them together and fairly easily turn them to sandy gritty dust. They are not as hard as traditional red clay bricks. The photo to the right is what is known as a "split." It is like a full-sized fire brick, but only half as thick. You may wish to buy both sizes of fire bricks as you come across different uses for them in your ceramic cooking. Also, fire brick can be broken into pieces to create special different sizes. For example, full sized fire bricks cut in half make nice posts to place a second grid on in order to make a raised grid.