Peek-a-boom

A Peek-a-boom is a X-Naut-like enemy appearing in Wario Land: Shake It!. At first, they are invisible. If Wario came closer, it appears with a cloud of smoke. But if Wario comes too close, it vanishes again, with more smoke. These enemies throw bombs to attack Wario. Sometimes, Wario needs these bombs to solve puzzles, which let him get to treasures. If Wario uses an Earthshake Punch, when he is close to it, he would pick it up and shake it.

Trivia

 * Its name is a pun on the phrase Peek-A-Boo and the exploding sound Boom.