Mystery Metal Monkey

The Mystery Metal Monkey Is a rare enemy in Mother 3. It is found in Argilla Pass despite its low HP count, it has a high defense, making it hard to beat by normal means. When defeated, it yields a "good experience" which is worth 0 exp. It is a parody of the Metal Slimes found in the Dragon Quest series, infamous for being hard to defeat spewing out large amounts of experience.

Battle Memory description
"Fighting this metal monkey will result in quite the experience. Just keep that in mind."