Fungus balls are tangled mats of hyphae that are often found in the maxillary sinus. In approximately half of affected patients, radiologic evaluation will reveal areas of hyperdensity within soft-tissue masses. Histopathologic examination will reveal no invasion of the mucosa and no granulomatous reactions. Surgical removal is sufficient because fungus balls are not known to recur. We describe an interesting case of a sinonasal fungus ball that resembled dental filling material on radiologic imaging because of its extraordinary radiopacity. Histopathologic examination detected eosinophilic infiltration, hyphae in the submucosal tissues, and tissue necrosis.