Drokkvid

 was a carnivorous alien. When Miss Brayley found the Drokkvid in her plants, she thought it was hurt, so she gave it lunch, accidentally making it become a giant creature, that ate all of Rolle Hill School's food. The Eleventh Doctor and Clara Oswald searched for it. Upon entering the school, they found it had returned to its original sound. (COMIC: Teacher's Pet)