Haemozoin is a disposal product formed from the digestion of blood by some blood-feeding parasites. These organisms such as malaria parasites (Plasmodium spp.) digest haemoglobin and release high quantities of free haeme, which is the non-protein component of haemoglobin. A haeme is a prosthetic group that consists of an iron atom contained in the center of a heterocyclic porphyrin ring. Free haeme is toxic to cells, so the parasites convert it into an insoluble crystalline form called haemozoin. In malaria parasites, haemozoin is often called malaria pigment.