Real Bombchu

Introduced in Majora's Mask, Real Bombchu (本物のボムチュウ, Honmono no Bomuchuu) are an organic, living version of the Bombchu bombs introduced in Ocarina of Time (and present in Majora's Mask). In-story, they are probably the source of inspiration for the mechanical Bombchu. These critters run around with bombs hanging from their tails, waiting to blow themselves up in order to damage their enemy. Simply run away from them and they will explode behind you. If you want to do some target practice, shoot them with an arrow from a distance. In addition, if Link raises his shield when facing a Real Bombchu, it will bounce off, fall backwards, and explode.

The Wind Waker
Bombchu are also what Rats holding a bomb are called in The Wind Waker. They are most prevalent as the main inhabitant of the Forsaken Fortress.