Within the CHAT community there is an ongoing discussion about the concept of activity (Gegenständliche Tätigkeit). How is activity to be understood, what are its core related concepts, how to delimit it, what is its ”unit” and its relations to actions and strings of actions, is it applicable to individuals as well as collectives - these are some of the questions posed and debated. The paper is intended as a contribution to this discussion on activity. My entrance to the discussion will be to focus on how artefacts are transformed in the course of collaborative work at an angio clinic. Thus, in the paper my practical point of departure is a detailed empirical case of the construction and use of a central artefact at clinical coronary diagnostic work. The artefact is called angiography (”angio” in everyday talk of the participants). The angio is an x-ray based visualization of the coronaries as the outcome of the injection of a radiopaque substance. The angio is constructed in several steps. First, a digital computer-based representation is constructed, then it is reconstructed, added on, and transformed into paper format. It is (re)designed for several situations and audiences, for individual and joint consultations. The case I will present accounts for the full cycle of the patient angiography, from its production and uses until the patient is considered having got a final diagnosis and a treatment recommendation. A predominant theme of CHAT discussions about the motivating role of the object of activity has been the motive of the individual. This is a legitimate psychological perspective. As I grasp it, it is a stance that takes precautions to preserve the individual subject´s role in activities, putting agency in individual subjects and not in ”systems” of any kind. My perspective will be different. The focus is the object of activity as a motive of the collaborative work. It is a motive guiding the overall work process, ”keeping the activity of work together” so to say. I take for granted that this overall motivation, related to the object of work, ”in some way” influences the participants individual motivations as well. (I do not address how this works.) Agency is about actions of human beings. However, in the paper I argue that it is reasonable to talk about agency related not only to live actions, but to ”fossiled” human activity as well. At least, there is a potential agency-character in artefacts (”by the agency of”). This is a corollary to the artefact-mediatedness of activities. By the agency of certain artefacts, some activities are being enabled. Without earlier generations´ generating of artefacts that we now can use, today´s activities wouldn´t exist. A major argument in the paper is that artefacts are instructive, and that they are instructive because they are made instructive. There is a stamp of human activity on artefacts, a stamp that is recognizeble as distinctively human. (This is the ”ideal object”, in my reading of Ilyenkov, an ”ideality” that is ”built-in” into every artefact.) The core of the work activity at the angio lab can be described as the design and redesign of angio graphic artefacts. In other words, in their work practice the Thorax team has to take, and takes, artefacts seriously. I suggest that we as researchers of their labor have to do the same thing in order to make their work visible and improve our activity-theoretical understanding of what is going on when the job gets done.. An often used characteristic of activity by CHAT scholars is that activities are ”artefact-mediated and object-oriented.” The conclusion of the paper is that if we better want to understand the artefact-mediatedness and the object-orientedness of activities, we have to take artefacts more seriously than most of us have done so far. In sum, the arguments of the paper are: 1. Artefacts are instructive, and the reason why they embody this feature is that they are designed to be instructive. 2. Artefacts are ideal as well as material/corporeal. 3. There is a certain form of agency related to artefacts (although not symmetrical to human agency). 4. The object of activity ”keeps the activity together” by being collectively motivational. 5. There is a need to take artefacts more seriously in studies by CHAT scholars.