A case of a parasitic perineal monstrosity from the collection of the Pathology Museum of the University of Florence, is described on the basis of the original medical records and illustrations. The surgeon Giorgio Pellizzari (1814-1894) first reported this extraordinary case of sacrococcygeal teratoma containing a rudimentary inferior limb. Reader of Descriptive Anatomy, Pellizzari was a well-known Anatomy Dissector and Curator of the Physiological Museum of the Regio Arcispedale di Santa Maria Nuova in Florence. This report underlines the importance of studying the archive material in order to thoroughly comprehend a single museum talking object. This handling of matters will help to turn anatomical collections into a unique teaching toolfor modern medical practice and a noteworthy documentation of scientific, artistic and historical value. Through analysis of the original catalogue and investigation by means of modern scientific techniques, discovering the story behind the object becomes afeasible challenge.