Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which contains both of those minerals) and is the main component of pearls and the shells of marine organisms, snails, and eggs.
An ordinary breath for a 70-kg adult is about 500ml of air. We call this the tidal volume. Since oxygen is 21% by volume of air, then the volume of oxygen inhaled is about 105ml. The density of pure oxygen at sea level is 1.43kg per cubic metre.
The density of air at sea level is about 1.2 kg/m3. Our lifetime of breathing (about 265,083 m3) thus involves about 318,100 kg of air. So if you weigh 70 kg you breathe over 4,500 times your own weight in your lifetime. You breathe about 13 kg of air per day, which is more than you eat.