Mechanical fish

Drill Fishes are yellow, submarine-like enemies in Wario Land 4. They are grey-colored fishes that wear a wooden armor with a drill in the front of it. They also have little pipe in their back and grey fins. Drill Fishes work for Catbat and are found in Sapphire Passage. They're found in one high wate channel in Catbat's room.

They swim from left to right, and can be only attacked from behind, and, if it's attacked by the front, it will damage Wario. This is very similar to the Pirate Gooms, from Wario Land: Super Mario Land 3.