Sinja Rist investigates the effects of microplastics, which are widespread in marine sediments worldwide, on the green-lipped mussel Perna viridis. She demonstrates that after a 6-week laboratory exposure to increasing particle numbers, significant impairments in physiological functions such as filtration, respiration, movement, and byssus production occur, along with increased mortality. Significant effects were measurable even at low particle concentrations. Overall, the results of this study suggest a marked depletion of the mussels' energy reserves. In contrast, the contamination of the particles with the organic pollutant fluoranthene did not have a clearly measurable effect on the animals. This study highlights that, in light of increasing microplastic pollution in benthic habitats, various impacts on organisms must be anticipated.