Likely built sometime around 450 CE, the 23-foot-tall iron pillar found in Delhi's ancient Qutb Complex amazed both locals and scientists because of its seeming resistance to rust. Theories about the "out-of-place artifact" abounded, with one explanation being that it was built by aliens, since local people at the time couldn't have built such an element-resistant object.

But recent scientific analysis showed that not only was such a feat well within the capabilities of ancient people, it also revealed exactly why the pillar doesn't rust. It's coated with a thin layer of iron hydrogen phosphate hydrate (also called misawite), which keeps the elements out. The film likely ended up on the pillar through a combination of impurities in the iron and the primitive ovens the metallurgists were using. No ancient astronauts needed.