Pebble

Pebbles are an attack item in Paper Mario. They are found on Shiver Mountain and can be thrown at enemy monsters, but are used best as substitutes for more valuable items in caves on Shiver Mountain. In a certain area, items keep open doorways, and if the item is taken the door closes. Pebbles can be traded for those items in an Indiana Jones-style swap.

A Pebble does one damage to a single enemy, and nothing more. But if a Pebble appears on a Mystery? roullete, it will hurt Mario instead, with 5 HP damage.