The extent of plastic pollution remains largely hidden from view in the form of microplastics (MPs): plastic particles with diameters less than 5 mm. Since plastics are slow to degrade, they fragment into tiny particles that end up contaminating entire ecosystems. In the years since their discovery in the early 1970s, MPs have become a ubiquitous and global concern. MPs are found in land, air, water, and the food that we eat, especially seafood. This is because freshwater sources, such as rivers, often carry off MPs into the oceans, where they accumulate.