Interactions with various suspended soils and natural colloids are important but poorly understood aspects of microplastic (MP) behavior in aquatic environments. The result of these interactions is the formation of aggregates, where MP are incorporated together with live and dead organics, so-called marine snows. The vertical transport of organic substances, including living cells, represents an essential part of the carbon pump exporting organic matter from the photic zone to the deep ocean. Plastic particles have been found in marine snow along the water column as well as in sediments, implying that sinking aggregates could be an efficient export mechanism of MP to the deep ocean. However, it is unclear whether the sinking rate and the associated carbon pump processes can be affected by MP at the ecologically relevant abundances of the plastic litter. In MOTION project, we focus on reviewing interactions between MP and other particles ubiquitously present in pelagia and analyze the kinetics of the aggregate formation, their settling characteristics, and the role of microorganisms in the aggregation. The project is funded by the Swedish Institute.