A person that eats stones to entertain.

Similar in a way to the geeks of the common sideshow, a lithophagus entertains a crowd by ingesting stones and gravel to impress the audience.

As documented in William Hone's Table Book of Recreation (1827):

"He not only swallowed flints of an inch and a half long, a full inch broad, and a half an inch thick, but such stones he could reduce to powder, such as marbles, pebbles, etc. he made into paste, which to him was a most agreeable and wholesome food. He recalled, 'When I went to school, I was a great favorite with the boys, for whenever there was a damson tart or cherry pie, I was well content to eat the stones and leave them the fruit'..."

I am not aware of any dedicated lithophagus acts touring the globe right now, however I did see a fellow perform some stone-chewing at a freak show in Hamilton, Ontario last year, which did indeed impress me significantly.