Psilocybin hallucinogen molecule. Molecular model of the hallucinogenic drug psilocybin. Psilocybin is a psychoactive alkaloid found in hundreds of species of mushrooms, known as magic mushrooms. When ingested it causes euphoria, hallucinations and an altered perception of time. Atoms are colour-coded: carbon (grey), hydrogen (white), nitrogen (purple), oxygen (red) and phosphorous (orange).