Danny was a boy who became the host of a Harmonelid one night when it became buried in his ear.
The Eleventh Doctor detected the worm's presence and somehow lured Danny and his dad to a nearby hospital in Leeds.
An investigation into Danny's ear with the sonic screwdriver caused the Harmonelid to flee. It settled in the ear of Mr Richards, a deaf patient whom the worm could not harm. (COMIC: Earworm)