Paper Mario: The Origami King features a funny and interesting storyline that has you completing a number of tasks.
In order to continue the story, you'll need to locate the Shell Stones.
How To Find The Shell Stones In Paper Mario: The Origami King
There are four Shell Stones in total and fortunately, they are all found as you may your way around Overlook Mountain.
The first one can be found being sold by Monty Mole - he is located at his shop stand with three Koopas crowded around.
After talking to him, he will auction off the prize for 10,000 coins. You can repeatedly say no to his offers until you work him down to 500 coins.
The next one is located behind a wall, located near the base of the mountain behind a save block, that needs to peeled off using the 1000-fold arms.
You'll spot a Dry Bones holding the stone, who appears to be dead, but is actually just "dehydrated". It will give you the stone and run off.
Next, if you walk off to the right of the mountain's base you'll notice a fishing pole on a dock. Use the fishing rod to fish and catch one.
Once you've caught one, you'll enter a battle and once defeated it will relinquish the stone.
Finally, you will need to climb as far as you can go up the mountain until you reach Toad Tower. At this stage, you won't be able to enter the tower.
Head left of the tower and down a slope until you reach a garden with three macho Shy Guys.
The Shy Guys will aim to keep the stone away from you by kicking it to each other. You need to try and knock enough of them over with your hammer and force them to kick the ball to one that is lying on the floor.
If you can do it successfully, the stone won't reach the Shy Guy and you can simply pick it up.