The Pauli Exclusion Principle has been considered as the most important and well-studied outcomes of quantum mechanics. It states that particles like electrons cannot hold the same quantum state.  Over the years, physicists have been figuring out the more subtle consequences of the principle and came up with several theories. Now, Marvin Holten and colleagues from Heidelberg University in Germany predicted the Pauli exclusion principle should create spectacular crystals. Now they’ve found them for the first time. They have termed unusual things as “spectacular geometric structures.” Researchers believe their work lays the foundation for future studies of associations in strongly interacting systems of many fermions.