In the seventeenth century, red coral was a popular Galenic simple in early modern England, imported from busy ports such as Livorno and Marseilles to the Port of London. It was a bestseller in apothecary shops and frequently listed in receipt books. Pharmacopoeia Londinensis of 1618, translated into the vernacular by Nicholas Culpeper in A Physical Directory (1649), attributed red coral medicines to Galen and Culpeper himself interpreted coral’s medicinal benefits within the Galenic framework. However, with increasing interest in experimental medicine and new theories of drug action in the latter half of the seventeenth century, some physicians began to suggest that coral’s properties allowed it to change and regulate the body in different ways. This chapter employs the example of Corallium rubrum as a prism to explore how a Galenic simple was interpreted, modified or rejected by physicians in early modern England. Rather than viewing Galenic medicine in opposition to newer theories of chemical medicine in the seventeenth century, analysis of one simple—in this case, red coral—demonstrates remarkable consistencies in the perceived benefits of this ancient remedy and its relevance to the pragmatic concerns of the period.