Breakable blocks can be destroyed by being shot or hit from below with the player's head. Blocks tinged with the secondary color (the defualtcolour being red) will drop 10 gems when destroyed. Landing on breakable blocks will end the current combo.
These blocks appear as blocks of dirt in World 1, crates in World 2, and pieces of coral in World 3. World 4 has a notable lack of any kind of block, solid and breakable.
Breakable blocks also form a 3 by 12 "wall" before the Boss.
If the player has the Gunpowder Blocks upgrade, when shot, breakable blocks (and any other blocks adjacent to them) will shoot a single shot upwards. This shot has the same size, range, and damage of a shot from the Machine Gun.