Bombchus

Bombchu is a word used to describe two things in the Zelda universe: a type of moving bomb or a rodent enemy which attack by using bombs.

Ocarina of Time
In this game, bombchus were a type of bomb which, when lit and placed on the ground, would scurry away in a straight line along the floor and walls until its fuse ran out or it hit an impassable object, at which point it would explode. They have a vaguely mouse-like appearance and could be bought from a specialist shop in Hyrule Castle Town, from a merchant on a flying carpet in the Haunted Wasteland, or found in chests scattered throughout Hyrule. They were also used in the Bombchu Bowling Alley.

Majora's Mask
In Termina, 'bombchu' also refers to a type of enemy, fully titled 'Real Bombchu', resembling a mouse, with a bomb on its tail. These volatile creatures would use this to attack Link or anyone else who invaded their territory, but could easily be repulsed by holding out a shield in defence and letting them bounce off, stunning them and leaving them to be killed by their own bombs.

The Wind Waker
The living 'real' Bombchus made a reappearance in The Wind Waker, but on this occasion they bore a much stronger resemblance to rats and had to rely on picking Bomb Flowers and throwing the fruit at Link rather than having their own tail-bombs. Typically they attack in groups, surging out of their rat-holes, each grabbing one bomb, and throwing them at Link before retreating back to the holes to prepare for a fresh assault. They are invulnerable whilst hiding in these holes.

Despite being organic creatures, these Bombchus do not have 'Real' in their names.

They can be distinguished from normal Rats by their distinctive white face patterning.