For eons, the debris has contained the same things — flecks from plant and animal carcasses, feces, mucus, dust, microbes, viruses — and transported the ocean’s carbon to be stored on the seafloor. Increasingly, however, marine snowfall is being infiltrated by microplastics: fibers and fragments of polyamide, polyethylene and polyethylene terephthalate. And this fauxfall appears to be altering our planet’s ancient cooling process.
Source: wiktionary