Croakoa is a magical substance. Chocolate Frogs are composed of seventy percent finest Croakoa. It is possible that is this substance that makes the Chocolate Frogs act like real frogs.
Croakoa is a portmanteau word combining "croak", referring to a fog's cry, and "cocoa", referring to the beans used to make chocolate. Chocolates usually list their cocoa content, in the same fashion, and most fine dark chocolate has a cocoa content of around seventy percent, which is how much Croakoa is in Chocolate Frogs.
- Harry Potter and the Prisoner of Azkaban (film) (Mentioned only)