Shell on Wheels is an achievement in Plants vs. Zombies 2. It requires the player to place a Wall-nut on a minecart. It is worth 5 points in the Game Center and 500 XP on Google Play Games for Android devices.
Having a Wall-nut in a minecart not only unlocks Shell on Wheels, but it also has a high practicality. Having it there allows the player to share a Wall-nut across multiple lanes. The only down-side is if the Wall-nut is shared among lanes, it will be eaten faster and need to be re-planted or repaired more often. This is especially helpful combined with Wall-nut First Aid and Plant Food when the Wall-nut has low health. It also serves as a buffer for the other plants. This can be done easily in any of Wild West's Last Stand levels, as the player can plant it immediately without waiting for its recharge.
- Playing Wild West's Save Our Seeds levels does not count towards the achievement. This is because the Wall-nuts are not actually planted by the player, but instead are automatically placed there because they are endangered.
- It and Pod Squad are the only achievements that require planting plants on minecarts to be achieved.