According to The History Channel: "If ancient aliens visited Earth, what was their legacy, and did they leave behind visible indications like advanced aircraft, complex electrical grids, and elaborate building machinery? Vimanas are described in variable but vivid detail in Indian Sanskrit scriptures dating back to 6000 B.C. Egypt's megalithic stone buildings provide evidence of precision saw work. Interpretations of Jewish Zohar writings show a life-sustaining manna machine that resembles chlorella algae processing systems today. Is this modern technology, or is there evidence that these amazing technologies existed on Earth thousands of years ago?"