Bug Block

Bug Blocks (バグブロック, Bagu Burokku) are computer bugs in the shape of a cube that appear as a critical part of the gameplay in Kingdom Hearts coded.

Kingdom Hearts coded
Bug Blocks appear in all of the data worlds from Jiminy's Journal; they are a product of the data "bugs" from digitizing the journal. The Data Sora must destroy Bug Blocks in order to progress through worlds and the storyline, as well as fix the data worlds.

In Episode 8, it was revealed that Naminé's manipulation of Sora's memories in Kingdom Hearts: Chain of Memories was the primary cause of the appearance of the Bug Blocks. The data Naminé confirmed this to King Mickey and the Data Sora, along with informing them of the suffering of some connected to Sora's heart, namely Terra, Aqua, Ventus, Roxas, the real Naminé, Axel, and Xion.

Varieties
There are different types of blocks with different designs and effects. Kingdom Hearts Re:coded added additional blocks and color coding.
 * Normal Blocks (ノーマルブロック): Breakable blocks. Colored red and marked with a design resembling organic circuit lines with circular patterns.
 * Metal Blocks (メタルブロック): Unbreakable blocks. Colored silver with the same markings as Normal Blocks.
 * Damage Blocks (ダメージブロック): Blocks that inflict damage on contact. Marked with a jagged thorny pattern. Colored red in Kingdom Hearts coded and yellow in Kingdom Hearts Re:coded.