The Meridiani Planum (alternately Meridiani plain, Meridiani plains, Terra Meridiani, or Terra Meridiani plains) is either a large plain straddling the equator of Mars and covered with a vast number of spherules containing a lot of iron oxide or a region centered on this plain that includes some adjoining land. The plain sits on top of an enormous body of sediments that contains a lot of bound water. The iron oxide in the spherules is crystalline (grey) hematite (Fe203).