Troll cobbles

"It was a horrible sight. Twelve feet tall, its skin was a dull, granite gray, its great lumpy body like a boulder with its small bald head perched on top like a coconut. It had short legs thick as tree trunks with flat, horny feet."

- Description.

Troll cobbles is the name given to the horny growths that often cover the thick skin of trolls. Trolls periodically seem to shed these growths, which litter the floor of their caves.

Appearances

 * Harry Potter and the Philosopher's Stone
 * Harry Potter and the Philosopher's Stone (film)
 * Harry Potter and the Philosopher's Stone (video game)