It is a bulb so famous that it has its own website, a profile on Facebook and even an exclusive camera that films it day and night.
It is called the Centennial Bulb and according to the Guinness Book of Records it is the focus of light that has been on for a longer time in history.
It is located in an original site: a fire station in the city of Livermore, in California, United States.
It turns out that at the beginning of the last century, in 1901, firefighters wanted to illuminate their barracks day and night, to be ready to take action when necessary.
Then a local businessman donated the lamp, which had been manufactured by the company Shelby Electric Company, and firefighters left it on permanently, replacing the kerosene lanterns they used at night.
Decades passed and, except for some power outage or a move, the light bulb kept shining.
In 2001, at the turn of a century, it was officially named the Centennial Bombilla.
Incredibly, on June 18, it was 117 years old and with more than a million hours of use, it's still working!
Transfers
The firemen who installed the lamp at the beginning of the last century had their headquarters in a workshop that they shared with the police. When both departments moved to City Hall, the light bulb moved with them.
In 1976, when the light bulb had already entered the Guinness Book of Records, firefighters moved back to a new headquarters.
California authorities carried out a major operation to take care of his famous bulb during the transfer.
For starters, they cut the cable, for fear that unscrewing the bushing could break the glass. Then, a fire truck and the police escorted the light bulb to their new home: the fire station number 6, where it continues to shine today.
According to the records, the lamp only remained off for 22 minutes when it moved.
In fact, the evidence suggests that he never spent a whole day without functioning.
What is it made of?
The Centennial Bombilla was blown by hand in 1897 by the Shelby Electric Company, an Ohio company that ceased to exist.
The founder of the company was the French Adolphe Chaillet, a much less known rival of the famous inventor Thomas Edison.
The Chaillet bulb measures about 8 centimeters and has a more rounded shape than modern lamps.
While it is believed that it was originally a 30-watt bulb - the modern ones are usually 40 to 200 watts - over time it was reduced to 4 watts, so it emits a dim light.
That seems to be one of the secrets of why it has lasted so long.
But another key is inside: in 2007 the physicist Debora Katz of the US Naval Academy He analyzed other light bulbs from the same collection as the Centennial - which can not be touched for fear of breaking - and discovered two substantial differences with the current ones.
First, that its filament is about eight times thicker than that of a current light bulb.
And secondly, that filament, possibly made of carbon, is semiconductor.
That is semiconductor, explained the specialist, means that when the bulb heats up it becomes a superior conductor, unlike what happens with the current bulbs that when heated lose their function.