Jaw of Sea Wolf (Burges Collection of Materia Medica, late 1700s)

The label on this specimen identifies it as the jaw of a wolf fish (Anarhichas lupus), ‘whose molar teeth are commonly called Toad Stones’. Toad stones were believed to come from the heads of toads – hence the name – but were actually the small round teeth of fish. They were said to be powerful poison antidotes, sometimes even ‘sweating’ in the presence of poisonous substances, and so were highly prized and considered gemstones.

Sweet are the uses of adversity, Which, like the toad, ugly and venomous, Wears yet a precious jewel in his head

Duke Senior in Act II, Scene I of William Shakespeare’s As You Like It