Hemozoin

thumb|250px|right|Plasmodium falciparum hemozoin crystals under [[polarised light.]] thumb|Plasmodium ovale microgametocyte in Giemsa-stained thin blood film, with annotated [[Schüffner's dots and hemozoin pigment.]] Haemozoin is a disposal product formed from the digestion of blood by some blood-feeding parasites. These hematophagous organisms such as malaria parasites (Plasmodium spp.), Rhodnius and Schistosoma digest haemoglobin and release high quantities of free heme, which is the non-protein component of haemoglobin. Heme is a prosthetic group consisting of an iron atom contained in the center of a heterocyclic porphyrin ring. Free heme is toxic to cells, so the parasites convert it into an insoluble crystalline form called hemozoin. In malaria parasites, hemozoin is often called malaria pigment.

Since the formation of hemozoin is essential to the survival of these parasites, it is an attractive target for developing drugs. It is much-studied in Plasmodium as a way to find drugs to treat malaria (malaria's Achilles' heel). Several currently used antimalarial drugs, such as chloroquine and mefloquine, are thought to kill malaria parasites by inhibiting haemozoin biocrystallization.