The crate might have been cut from the final game due to similarities to the "POW block" from the Super Mario series, along with its lack of usefulness in general.
It looks like a basic crate with a blue stripe on the top and bottom with the word "POW" written in yellow with a blue border on its sides. Earlier versions of the crate had red stripes and outlines instead of blue. Breaking it will cause red and blue explosions that will only break nearby crates.
The crate appeared in the following levels:
|! | ? | Activation | Aku Aku | Ammo | Arrow | Basic | Beenox | Big TNT | Block | Bounce | Checkpoint | Coco | Copter | Cortex | Crash | Detonator | Freeze | Infinity | Invisibility | Iron Arrow | Iron Checkpoint | Iron | Locked | Magic Carpet | Nina | Nitro | Nitro Switch | Outline | Pants | Slot | Spike | Time | TNT | World | X|