The Aegina Island in the Saronic Gulf is a prime location to gain valuable insights regarding sedimentation on volcanic islands due to its potential to exhibit rich Pliocene fossiliferous marine sediments into the insular volcanic propagated edifice. Although shallow-water shell beds generally appear to be extremely rare on such young (Plio-Pleistocene) exposed volcanic islands due to the limited sediment accumulation space in their narrow, steep, and high-energy insular shelves, the northern part of the island is exceptional since it exhibits well-preserved marine sediments among the volcanic sequences. The occurrence of a massive mollusc accumulation within the shallow-water deposits of Agia Marina is important to assess the benthic community dynamics, including taphonomic, palaeoecological, and depositional conditions, and furthermore to enhance our knowledge of the macroevolution response of the eastern Mediterranean biota to Pliocene palaeoenvironmental and palaeoclimatic conditions. The Agia Marina outcropping strata have previously been ascribed to the early Zanclean through combined biostratigraphic, magnetostratigraphic and radiometric datings. The main component of the fauna is the epifaunal mobile pectinids and ostreids, while the accompanying fauna consists of barnacles, echinoids, brachiopods benthic foraminifera, and fish remains. The relatively good preservation state of all the above bioclasts reflects rapid burial under high sedimentation rates, which was possibly favored by deposition on a platform laterally protected by volcanic rocks. The studied assemblage suggests a high-energy shallow-water environment (pectinids and barnacles) characterized by sandy substrate with the presence of hard substrate representatives (ostreids and echinoids), indicating topographical diversity with access to the open sea. The presence of key thermophilic taxa further suggests warm-water conditions in this setting, in accordance with those recorded in other time-equivalent Mediterranean sites. The data reported here provides new information on the coastal volcanic paleoenvironments during the Zanclean-early Piacenzian transition, paving the way for more focused studies in the eastern Mediterranean.