Appearance and behavior
Jack resembles a cyanoid blob with a small dotted face and a pale bulb attached to a string on its head, much like the light on an anglerfish. It hides in the Cannon until Kirby gets close, when it will occasionally pop out and attack him by spitting a star-shaped projectile. It cannot be harmed until it tries to attack. Another way to dislodge a Jack is by firing the Cannon.
Jack gives no Copy Ability when swallowed. Additionally, unlike most enemies, it will not respawn if Kirby leaves the screen and comes back.
Screenshot of Jack hiding in a cannon in Olive Ocean
Screenshot of Jack being blasted from a cannon in Radish Ruins