moon cell core (fate)
The core of the Moon Cell from Fate/EXTRA. The core of the Moon Cell is a gigantic photonic crystal, about 3000 kilometers in length and using light as its storage medium, as well as all of its high-level data control systems to transmit data and system commands. The giant photonic crystal slumbering beneath the moon can be considered a supercomputer of enormous size, incredible complexity, and immeasurable processing power that was created from such nanoparticles. Although most supercomputer development was abandoned in the 2010s in favor of shifting the focus to cloud computing, the processing power of the all digital media on Earth combined cannot hope to match the capabilities of the substance. According to Twice H. Pieceman, the Moon Cell's core is made of the purest type of photonic crystal, a material that can act like the crystals used on holography to recording media.
https://typemoon.fandom.com/wiki/Moon_Cell