The Antiquis Triangulum, or as it's more commonly referred to, the Pyramid, is a mysterious artifact left behind by Alexander Nigma after his death. Currently residing beneath A. Nigma High, the pyramid is a source of "unimaginable power" and is sought after by many people. When Elizabeth Mann, Art Wurst, Maxwell Finnwich and Lo Ping attended A Nigma High, they joined forces with their Principal, Alexander Nigma, to open the Antiquis Triangulum under the school. The four children transported the eclipse beam to the Pyramid by reflecting the light to each other. When it opened, Alexander Nigma stepped into the Pyramid and used the cipher to see what was in it.
The Pyramid first appeared in Outcast Times at A. Nigma High, where it served as a staircase to exit the tunnels. While it did not have much significance at the time, The Pyramid later became the centre of Season 3.In the show's third season, it is revealed that the Pyramid contains an unearthly power, and can only be opened during a solar eclipse. Niles Peg had attempted to open the Pyramid before, but had failed and Lynch Webber and the Unnamed Female Council Member did the same thing, causing him to fall into an eternal slumber. It is shown that it is protected by the cybernetically-enhanced Blue Tatzelwurms. The Book seems to contain information of the Pyramid, but it is in a language that only Finnwich has been shown to be able to read. The Pyramid can only be opened by using the two keys - one of which had been in Lee Ping's possession since the Season 1 episode 9 15th Graders.
In Season 4, it is revealed that Alexander Nigma, and some of his students had opened the pyramid, inside it was described to have "the answers to everything" along with two coffins, one upon opening turning what was ever inside to dust, and the other containing His Eminence. It was the resting place of the ancient creatures, of which "His Eminence" is a member, and presumably the leader, of, prior to their awakening in the series' final episode.