In museum collections, we attempt to conserve objects to preserve our material heritage and gain insights into the past. In a certain sense, such conservation practices aim at creating a state of suspended animation, where objects hibernate solely maintaining their most vital functions for us, such as their significance for our material heritage and value for future knowledge. By establishing such a hypometabolic state of reduced metabolism resembling death, objects are ‘frozen’ and removed from the forces of time. In other words, we attempt to suspend time in order to preserve it. This temporal regime constitutes the possibility for the objects to reappear and come back to life in exhibitions and research. Metaphorically speaking, objects live and die at the museum. For example, they may crop up from hibernation providing new insights into the past, they may change cultural significance over time, or they may rest in oblivion. Yet more than metaphorically speaking, indeed, quite literally and metabolically, objects not merely change meanings and provide new avenues for research over time, their very materiality transforms. Even though we attempt to suspend their life processes, objects change and decay over time. While we aim at permanence and stability, impermanence is always already trespassing on our sacred grounds at the microscopic level. Collections are more metabolic than we (like to) think. This realization opens a provocative questioning into the temporal regime of museums: if objects transform naturally, is the function of the museum always to hinder this process and avoid collections becoming ‘metabolic’? If we accept the pervasiveness of life processes always already transforming our collections, then, how can we conceive of a living collection not merely in a hypometabolic and metaphorical sense, but as a truly metabolic collection? And what would be the value of such a cultured impermanence in contrast with the traditional value of conservation? Drawing on my dual role as researcher and curator at the Center for Basic Metabolic Research and Medical Museion, I will explore such questions through concrete examples from scientific collections and the rich collection we have at Medical Museion. Such examples will enrich the conceptual reflections on the permanence and ephemerality of collections and provide the basis for arguing that impermanence not necessarily leads to oblivion and loss of knowledge but may be a crucial condition for the becoming of future knowledge.