Numerous new records of tropical non-indigenous species in the Eastern Mediterranean highlight the challenges of their recognition and identification.

New data on 52 non-indigenous mollusks in the Eastern Mediterranean Sea is reported. sp. (aff. aptus sensu Blatterer 2019), Albano, Bakker & Sabelli, , Cerithiopsis sp. aff. pulvis, Albano & Steger, , sp., sp., Iravadia aff. elongata, aff. sp. 1 (sensu Blatterer 2019), , Parvioris aff. dilecta, Odostomia cf. dalli, , , , , , , , Musculus aff. viridulus, , Scintilla cf. violescens, and are new records for the Mediterranean. An unidentified gastropod, Skeneidae indet., sp., sp., sp., Vitreolina cf. philippi, (s.l.) sp. 1, (?) sp., and Semelidae sp. are further potential new non-indigenous species although their status should be confirmed upon final taxonomic assessment. Additionally, the status of , and is changed to non-indigenous, range extensions for nine species and the occurrence of living individuals for species previously recorded from empty shells only are reported. Albano, Bakker & Sabelli, is described from the Red Sea for comparison with the morphologically similar Albano, Bakker & Sabelli, The taxonomic part is followed by a discussion on how intensive fieldwork and cooperation among institutions and individuals enabled such a massive report, and how the poor taxonomic knowledge of the Indo-Pacific fauna hampers non-indigenous species detection and identification. Finally, the hypothesis that the simultaneous analysis of quantitative benthic death assemblages can support the assignment of non-indigenous status to taxonomically undetermined species is discussed.