From WiKirby, your independent source of Kirby knowledge.
Big Missile is an enemy that debuted in Kirby: Triple Deluxe, first encountered in the Lollipop Land level. It can only be defeated with the Hypernova ability.
Big Missile is essentially a giant missile with a shark-like face painted on it, making it similar to a Bullet Bill from the Mario games. It can't be swallowed with Hypernova, but it can be sucked in and spat back out again. To defeat Big Missile, Kirby must spit the missile out at its launcher to destroy it.
The launcher, which will attempt to assemble another Big Missile.