Agile software development has emphasis on human relations and fast paced changes in the project requirements. Extant Agile development literature focuses on team and organisational aspects of Agile development projects. The tools and artefacts used for project collaboration are currently not thoroughly researched. This research aims to find out how boundary objects are used to ensure collaboration over the Agile development project lifecycle. We selected case projects where a customer organisation was engaged with a vendor organisation in an Agile setting. Fifteen semi-structured interviews were conducted with the informants from both organisations. Our study reveals three different archetypes of boundary object: process objects, projective objects and infrastructural objects. The object archetypes respond differently to the frequency and magnitude of change. This paper enhances understanding of boundary objects aspects of Agile project development, suggests a novel way to categorise object and highlights some of the pitfalls than can result from misunderstanding object use.