Stubborn rocks

Because this subject has no official name, the name "stubborn rocks" is conjectural.

A set of stubborn rocks in the Distant Tundra.

Stubborn rocks^[1] are walls of stones in Pikmin 3 that can only be destroyed by pushing iron balls down a slope. They cannot be locked-on to, as there is no way to destroy them without a ball. They also don't appear on the radar in any mode but Side Stories, where they're represented with black ovals. In this mode, they're found in every day except The Ship Restored, but are never paired with iron balls, instead acting as undestroyable barriers or cosmetic additions, alongside cinderblocks and wooden signs.

Locations

The following article or section is in need of assistance from someone who plays Pikmin 3 Deluxe.
Particularly: List all Olimar's Comeback locations.

Story Mode

Distant Tundra: One wall at the exit of the cave where Brittany lands upon first arriving in the Distant Tundra. It must be destroyed to exit the cave and start the day properly, without the use of glitches. Another is found in the northern section of the main area with the geysers and Arctic Cannon Larvae. Destroying it gives access to the large cave system where the Vehemoth Phosbat is found. Two leaders must be used to access the ledge where the iron ball can be pushed down from, restricting access to the cave until Alph and Brittany are reunited. This one is surrounded by 2 snow pillars resembling those of dirt walls.

Bingo Battle

Jigsaw Fortress: One wall in layout B, which can be destroyed by pushing an iron ball at the top of the toy castle.
Rusted Labyrinth: Two walls neighboring eachother in the center of layout C, which can both be destroyed with a single iron ball.

Side Stories

Flower Garden: One set where the dirt wall near the base is in Story Mode, a string of 3 half submerged in the dirt around the elevated Sunseed Berry near the base.
Inside Forest: A string of two walls near the north shore next to a cinderblock, a string of 6 walls going into the central pond next to 2 cinderblocks.
River: A wall blocking off the southern section of the area next to a cinderblock.
Tundra: A wall where the bamboo gate is in Story Mode, one next to the stump, two and a string of two blocking off the northern land of the river.
Pikmin Reunion: A string of 2 walls next to a cinderblock blocking off the northern section.
Creature Hunting: One wall blocking off where the entrance to the Calcified Crushblat arena is in Story Mode, one next to it, one on either end of where the yellow bridge is in Story Mode, one next to the northern yellow bridge one, one blocking the 3 leader puzzle stump, a string of 2 where the base is in Story Mode, one blocking the entrance to Alph's crash site, a string of 3 and a string of 2 blocking the northern part of the area.
Land, Sea, and Sky
First Part Found
Team Monster Hunt
Channel Gone Dry
Looking for Louie
Big Fruit Carnival
Another Part Found

Gallery

This article or section is in need of more images. Particularly:
A good photo of a "string" of connected stubborn rocks in Side Stories, also the 3 sets of stubborn rocks around the strawberry in Olimar's Assignment as they look odd.
You can help Pikipedia by uploading some images.