Bombs are the ammunition Hoppi fires to move around. There are two types of bomb; orange bombs, which explode upon impact, and red bombs, also known as grenades, which explode after some amount of time. [how long?]
Bomb explosions can move almost anything, including Hoppi, non-static blocks, and even other bombs. Bombs also break purple (breakable) blocks. All other types of blocks are interacted with the same way.
According to semi-official dream lore, the bombs are filled with milk. As such the entirety of doppelgänger and family are in a dream state