Spines from a magical fish.
- Zygmunt Budge used these in his Cure for Boils (BoP).
Inconsistency: The Shrake is a magical fish created in the 1800s to bother the fishing nets of Muggles (FB). So how could Zygmunt Budge, who lived in the 15th-16th centuries, include the spines in his Cure for Boils written before the Shrake was created? One way would be that Budge is still editing his potions recipes after death, since the Hogwarts Librarian believed he had left quite of bit of himself behind in his "dangerous" Book of Potions.