In 2017 the first confirmed interstellar object to pass through the solar system, 1I/'Oumuamua, was discovered. The existence of comets of interstellar origin had long been expected, but 'Oumuamua defied expectations, displaying a number of puzzling features. I will discuss our recent work in which we argue that these unusual features can be explained by 'Oumuamua being composed of nitrogen ice. I will then place this in context and discuss implications for the formation of planets and small bodies in the outer reaches of planetary systems as well as future prospects.