The present study investigates fossil terrestrial gastropod assemblages from the Quaternary Dhar Eddoum Formation near Moulay Bousselham on the northwestern Atlantic coast of Morocco. The main objective is to characterize the taxonomic composition of the malacological assemblage and to assess its paleoenvironmental significance within coastal depositional systems of the Rharb Basin. Fieldwork was conducted in two stratigraphic sections (Dhar Eddoum 1 and 2), where fossil-bearing clay–silt deposits were systematically sampled and lithologically described. The collected specimens were identified through morphological comparison with reference collections from the Scientific Institute of Rabat and taxonomically classified following MolluscaBase nomenclature. The assemblage includes seven species belonging to three gastropod families: Helicidae (Theba pisana, Otala lactea, Cornu aspersum), Trissexodontidae (Caracollina lenticula), and Geomitridae (Cochlicella acuta, Cochlicella conoidea). The fossils occur within fine-grained sedimentary units interpreted as low-energy coastal deposits, locally reaching up to 12 m in thickness and associated with lagoonal to backshore environments. The results indicate a mixed terrestrial malacofauna dominated by xerophilous and psammophilous taxa, suggesting the presence of open sandy habitats such as dunes and back-dune systems, alternating with more stabilized and locally humid microenvironments. This ecological heterogeneity consists of a dynamic coastal system influenced by alternating phases of aeolian activity, sediment stabilization, and possible post-depositional transport processes. However, this research has limitations, particularly the absence of new independent chronological dating specifically conducted on the examined levels. The adopted chronological model therefore relies on the dates already available in previous research, which allows the deposits to be placed in a general temporal and paleoenvironmental context. Despite these constraints, the studied assemblage constitutes the first documented record of fossil terrestrial gastropods from the Dhar Eddoum Formation and provides a reference dataset for the region. The study contributes to filling a significant gap in the malacological record of the northwestern Moroccan Atlantic margin and provides a basis for future stratigraphic, taphonomic, and geochronological investigations aimed at refining Quaternary coastal evolution models.