The Magical Menagerie
In Harry Potter and the Prisoner of Azkaban, Ron, Harry and Hermione visit the Magical Menagerie to choose Hermionie's pet. While there, Ron picks up a bottle of rat tonic for Scabbers (who, as it turns out, has bigger problems than his owner realizes).
Although these creatures are initially described as “jeweled tortoises” in
Harry Potter and the Prisoner of Azkaban, they are more conclusively
identified as fire crabs in JK Rowling’s book Fantastic Beasts and
Where to Find Them. The crabs, hunted for their valuable shells,
can shoot flames out of their rear ends as a defense mechanism.
This tonic label includes an homage to the children's book Mrs. Frisby and the Rats of N.I.M.H.
In it, a widowed field mouse seeks help from a group of intelligent lab rats who have
escaped from researchers at the National Institute of Mental Health.