Plastics are indispensable in daily life but have become a planetary threat. They can be produced as or degrade into microplastics (MP), which have been detected in marine and freshwater environments across the globe. Previous literature points towards the need for an interdisciplinary approach combining natural and social sciences in addressing the problem. This includes an understanding of the role of the public in aggravating and /or mitigating the problem, particularly regarding risk perception and associated behavioral responses. The current presentation reports an empirical study that aims to investigate laypeople's intuitive understanding of MP. For this purpose, we asked an online sample (¿N=1000) from the Norwegian public to state what they think when they read or hear the word ‘microplastics.' They were instructed that they should write down the first thing that came to their minds, and that their answer would ideally include a few sentences, although just some few words were fine, too, if they did prefer this themselves. All obtained answers were coded in accordance with a coding scheme, which was developed in line with prior psychological research on risk perception and mental models in an environmental context. The analyses attended to both the content and structure of the responses attempting to identify shared mental models, especially when it comes to beliefs about causes and impacts of MP. Understanding these mental models addresses some existing knowledge gaps in the social science literature on MP, which may assist in finding a societal response to an eminent environmental problem.