The exotic, invasive freshwater bivalve Corbicula fluminea (Bivalvia: Corbiculidae) has spread globally in rivers around the World within the last eighty years. Due to low inter-specific competition outside its native range, this mollusc often produces large quantities of shell within invaded rivers. These shells are deposited on alluvial bars during floods, potentially inducing changes in riverine geomorphological and ecological functioning. Based on observations undertaken on the middle Garonne River, we suggest that within invaded river systems, and at specific locations on alluvial bars, C. fluminea may represent a new factor contributing to the process of habitat construction and to the modification of the local physicochemical properties of the substrate. We suggest that deposited shells can be used as biochemical markers for several elements, such as heavy metals, and as geomorphic biomarkers for studying recent floodplain evolution and associated in-channel sedimentation rates.