Researchers determined the precise chemical structure of a synthetic compound related to psilocybin (the active ingredient in psychedelic mushrooms) using X-ray crystallography. The compound, 4-AcO-EPT, is designed to be converted in the body to a psychoactive substance with potential therapeutic benefits for depression and anxiety. The study resolved conflicting reports about the compound’s exact composition and molecular arrangement, showing it exists as a specific combination of three molecular components. This work demonstrates why chemists need to study actual crystal structures rather than relying solely on chemical calculations.