If you visit Mr. Mulpepper's or Slug & Jiggers Apothecary in Diagon Alley, among the remedies available for a few scant Galleons is unicorn horn. In his comprehensive catalog of plants and animals used for medicinal purposes, the French apothecary Pierre Pomet identifies five species of unicorns, though he is quick to admit that most unicorn horns sold in shops are probably from narwhals.  Narwhal or not, these horns were worn as protective amulets, used to cure fevers and rout poisons. They were also displayed as curiosities in pre-Revolution-era France.