Red is a red blood cell that has matured and is ready to begin its journey through the body. It was created in the bone marrow and its job is to carry oxygen from the lungs to the rest of the body. It travels to the heart where it enters the right side to be oxygenated before traveling to the left side and being pumped throughout the body. Red blood cells circulate for about 30-45 seconds, have a lifespan of around 120 days, then are removed by the spleen. They transport oxygen through veins and capillaries using hemoglobin, which gives them their red color.