Plastics are everywhere in nature and society. We cannot live without them, but at the same time they impact our environment. Plastics could become one of the most important environmental problems facing our society this century. Microplastics have been found in urban water, air, and soil, as well as in once pristine environments like the Arctic. Of concern is the fact that plastics break down into smaller particles (micro- and nano plastics) through physical and chemical reactions and are not biodegradable. • • • • How much of a risk do these particles pose to the environment and to human health is the crucial question. Compared to other pollutants, microplastics are different. There is evidence that most of their effects are mediated by physical parameters, such as particle shape and size, rather than by overt chemical mechanisms. Furthermore, their effects are usually sublethal (and may even be nominally positive in some cases). What is it about? How to deal with this wicked problem? From nano to macro, and from society to sea.