For nearly 500 years, the tomb of Polish King Casimir IV Jagiellon remained sealed beneath Wawel Cathedral. When the royal tomb was opened in 1973 for conservation work, no one expected the discovery to become one of history's strangest "curse" stories. Within the following years, members of the 12-person restoration team died prematurely, leading to rumors of a Jagiellonian curse.

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The mystery took an unexpected turn when microbiologist Bolesław Smyk identified Aspergillus flavus in samples from the tomb. The fungus can produce dangerous aflatoxins and its spores can cause serious respiratory infections under the right conditions. While scientists cannot definitively attribute every death to the fungus, the discovery provided a far more plausible explanation than a supernatural curse.