The Adeptus Mechanicus is the official Imperial name within the Adeptus Terra for the Cult Mechanicus or Cult of the Machine. In ancient times, before the current Age of the Imperium officially began following the end of the Horus Heresy, it was often called the Mechanicum. The Mechanicus acknowledge the Emperor of Mankind as the ruler of the Imperium of Man, but not the religious truth of the Imperial Cult or the Ecclesiarchy. Instead, the Mechanicus follows its own dark and mysterious scriptures and worships the deity they call the Machine God or the "Omnissiah." The Adeptus Mechanicus believes knowledge is the true manifestation of divinity in the universe, and all creatures and artefacts that embody knowledge are holy because of it. The Emperor is the supreme object of worship for Mankind, the living embodiment of the Machine God or Omnissiah, because he comprehends so much, understanding more about the true nature of reality than any other being in existence. The Adeptus Mechanicus also regard organic flesh as weak and view the removal and replacement of biological tissue with mechanical, bionic parts as sacred. Most elder Tech-priests have few organic parts left and eventually become more machine than man. The Adeptus Mechanicus is based on Warhammer Mars, the very first Forge World of the Imperium, and they are the sole rulers of the Red Planet. They provide the technical and scientific experts of the Imperium and field armies of massive Titans, Mechanicus Electro-priests, Skitarii and combat Servitors.