'Helicopter' Hieroglyphs

The Temple of Seti I in Abydos features an ancient Egyptian frieze that is believed by UFO enthusiasts and conspiracy theorists to be an out-of-place artifact, not unlike the infamous Dendera Light.

Among hieroglyphs such as the fly and whatnot, the engraving shows what seems to be a helicopter, as well as airplanes and a submarine. In some pseudoscientific circles, these hieroglyphs have been interpreted as a representation of modern technology in antiquity, knowledge perhaps given to the Egyptians by time travelers or extraterrestrial entities.

But most archaeologists agree that the carvings are nothing unusual. The hieroglyphs depicting "modern technology" are an example of pareidolia, our tendency to perceive a pattern or meaning that isn't actually there. Other examples of pareidolia include the perception of a human face in the moon or a church tower that looks like a chicken.

The real explanation behind the "helicopter" has to do with the legacies of different rulers. In ancient Egypt, it was common for hieroglyphs to be re-carved over time, especially when a new pharaoh came into power. Digital imaging has shown that these images come from two separate images on top of each other. The original carving, created during the reign of Seti I, translated to "He who repulses the nine enemies of Egypt." It was later remade by artists during the reign of Rameses II to read "He who protects Egypt and overthrows foreign countries." 

The plaster used to cover the Seti I inscription eroded over time, which led to the appearance of a single combined image. Conspiracy theorists have digitally altered photographs of the carving to remove details and make it look more like modern technology in order to support their pseudoscientific narratives.