A very large battle machine manufactured to be used in the ancient wars. It was rumored to be unstoppable. It went through a major re-design, doing away with the high-tech stomach panel, but its abilities stayed the same.
Its Japanese name is Merukaaba (メルカーバ), so it may possibly be a mistranslation of merkabah, a Hebrew word that means "thing to ride in" or "cart." The Merkabah is a Jewish cult that centers on the revelatory dreams of the throne of the Abrahamic God (much like this monster is connected to ancient history).