Mumbo Crates are small pink boxes found scattered in various locations across Showdown Town in Banjo-Kazooie: Nuts & Bolts. They are identified by Mumbo's skull on the side of them. When found, Banjo must drive them back to a small pink area outside of Mumbo's Motors to get Mumbo to open them. The crates contain parts for use with your in-game vehicles. Some items found in crates are rare, and are usually inside of the harder-to-find crates.
Some of the crates have small ghosts of dead pigs sitting on top of the crates. If talked to, they will talk about awaiting for the "fabled sirens call". To get rid of the ghosts, you must first defeat Gruntilda in the Terrarium of Terror, where you will obtain a Kazooie-like Horn. Once obtained, the "siren" may dispel the ghosts from the crates.
Stop 'N' Swop Crates
Stop 'N' Swop Crates are a type of Mumbo Crate found when you collect the appropriate
items in the Xbox Live Arcade version of Banjo-Kazooie. Nuts and Bolts will take when it recognize that you have found the items and place a in Showdown Town. The crates are colored according to the item found and contain special novelty parts (Fuzzy Dice, for example). The are only one of each of these items in the game (excluding however, the flag, as you get 2 in the box). While the game does show the location of the crates after collecting the item in Banjo-Kazooie, these crates are usually harder to find and require some thought.