Inscribed on the UNESCO World Heritage List in 1978, the Wieliczka Salt Mine is a monument of exceptional cultural, historical and geological significance. Its historic galleries and chambers expose Badenian (Middle Miocene) evaporites deposited within the Carpathian Foredeep Basin of the Central Paratethys, which have preserved a rich paleontological record. A particularly notable aspect of the mine’s paleontological geoheritage is the distinctive collection of microfossils assembled by Ewa Łuczkowska at the AGH University of Krakow during the 20th century. Containing over a thousand carefully prepared slides, the collection includes foraminifera, ostracods, bryozoans, radiolarians, and other microfossils. This micropaleontological material formed the basis for the development of biostratigraphy and our understanding of the paleoecology of the Badenian salt formations. The collection documents Middle Miocene chrono- and lithostratigraphic units, including the Wielician holostratotype in the Rarańcza Gallery, the Badenian facistratotype in the Kłaj-1 borehole, and the Wieliczka Formation stratotype. The microfauna samples preserved in the collection provide biostratigraphic information about tuffite-containing profiles that have been radiometrically dated. This has enabled the age of the so-called Badenian Salinity Crisis, which affected the Central Paratethys basins, to be estimated. This collection also documents locus typicus for the new species described here, including the Wielician index taxon Pseudotriplasia . E. Łuczkowska’s collection encompasses almost the entire, most important, 20th century record of micropaleontological research conducted at the Wieliczka Salt Mine. This diverse microfossils set up is of significant historical and scientific importance.