Skull art is not a new idea. Skulls have been used as art and decoration for centuries, but have gained immense popularity only recently.
As far back as 7200 B.C., skulls were displayed in homes in the Middle East, yet since that time period predates writing, there is no way of knowing the symbolism behind the displays.
Skulls of defeated warriors were displayed as trophies by Aztecs. About the same time, Mexicans began using skulls as symbols to celebrate the Day of the Dead, the days is still extremely popular on 2017 Mexico.