Almost all creatures have blood, but not all creatures’ blood is red. The red color of our blood results from the iron in the hemoglobin of red blood cells binding with oxygen. Oxygen is carried through our bodies via this process. Blood also fulfills numerous other roles essential to life, such as transporting nutrients and hormones, and recovering carbon dioxide, lactic acid, and other waste products. In addition, blood is equipped with outstanding defensive mechanisms that maintain its stable circulation; a particularly important example of this is hemostasis, which is directly involved in life-threatening situations. Blood is one of the organs fundamental to sustaining life.