Science and medicine rely on extra-textual objects. From within the array of instruments, models, specimens and other material culture this paper will focus on a specific medium (plaster of Paris casts) and a specific anatomy (the human head). Examples from medicine, anthropology and anatomy will illustrate the particularities of the process of casting, the relationships between interior and exterior, between life and death. Museum stores to this day hold thousands of these widely reproduced and circulated casts, their quantity bewildering, their status ambiguous. Unpacking their significance as clinical and scientific records in the decades around 1900 is revealing.