First, the wall lamp in the ancient tomb is made of mermaid fish oil, which can be used for thousands of years. This statement has a certain mythical color. It is said that there is a species that looks like people and fish. It is recorded as a shark in ancient books, which may be similar to the mermaid that people imagine now. Legend has it that this kind of fish is rich in fish oil, and because mackerel is actually a sacred object, its fish oil is different from ordinary lamp oil and can be kept in ancient tombs.
It was later confirmed that the lamp oil in the ancient tomb was only a mixture of whale fish oil and shark fish oil. Large fish such as whales and sharks are rich in fish oil, which is not only abundant but also high in fat, so it is often used in ancient tombs, but it is completely a rumor and can last for 2000 years.
Second, white phosphorus is added to the wall lamp of the ancient tomb, which will spontaneously ignite when exposed to air. In fact, the wall lamp in the tomb is not always on, but white phosphorus is added to the wall lamp. Because when the tomb is closed, it will cut off all the air, and the lamp oil of the wall lamp will not burn out. When someone finds the tomb and reopens the tomb door, air will enter the tomb. Then the white phosphorus in the wall lamp will spontaneously ignite when the air enters because of its low ignition point, so the wall lamp can be ignited.
The completion time of this process is very short, and the natural process of white phosphorus is almost imperceptible to the human eye. When opening the tomb, researchers may only see the result of the wall lamp burning, and they may mistakenly think that the wall lamp in the tomb has not been extinguished for thousands of years. But it's not like this, it's just the process of wall lamp rekindling, and people can't catch it in time. That's why there is such a misunderstanding. No lamp can burn for thousands of years without going out, and there is not enough oil and air in the ancient tomb.