The natural bluing process, also called bruising, occurs in psilocybin mushrooms. The bluing is due to the oxidative breakdown of psilocin by enzymes within the mushroom cells. In other words, bluing happens because some hallucinogenic ingredients in magic mushrooms break down. It effectively confirms that psilocin and psilocybin are, or at least once were, present in the mushroom. Furthermore, it is thought that more pungent mushrooms are more likely to bruise blue than weaker ones.