Pandorite

A Pandorite is a monster-in-a-box found in Super Mario RPG: Legend of the Seven Stars. Pandorites resemble squat, pudgy ghosts that disguise themselves as Treasure Boxes. As such, Pandorites can easily prey on unsuspecting adventurers searching for valuable treasure.

Mario and Mallow encounter a Pandorite while exploring the ghoul-infested Kero Sewers. In battle, the Pandorite proves that it is not only very clever, but that it is also quite powerful. The heroes discover that Pandorites possess both high physical attack and defense, and equally high magical attack and defense. In addition, almost all types of special attacks are ineffective against the treasure boxes (except for Mario's various Jump attacks). In battle, the Pandorite can wield exceptionally powerful fire magic, including the Flame and Flame Wall spells. The creature also uses the attack Scream, inducing the Fear status ailment and cutting an ally's attack and defense in half. Additionally, the treasure chest ghost uses the special technique Carni-Kiss, allowing Pandorite to voraciously bite a party member and cause significant damage. When it is not using special attacks, the specter inside the box occasionally reveals himself and assaults Mario's party. Eventually, Mario and Mallow overcome the Pandorite and continue their adventure.

Like real treasure chests, Pandorites are able to hold a considerable amount of treasure. After Mario and Mallow defeat the Pandorite in Kero Sewers, the heroes receive ten experience points, thirty Coins, a Flower Jar, and a valuable Trueform Pin. This Trueform Pin proved useful in the eventual battle against the guardian of Kero Sewers, Belome. Later in the game, if Mario returns to the Treasure Box that previously held the Pandorite of Kero Sewers, he will receive an additional fifty Coins. In fact, as soon as Mario leaves Pandorite's room, the Treasure Box will be filled with the Coins, meaning Mario can simply exit and reenter the room to claim the additional reward.

Pandorite is, in all likelihood, related to Hidon, Box Boy, and/or Chester, although the creature inside looks like what's inside a Cluster.

Trivia

 * Pandorite's name comes from the Greek legend of Pandora. According to the legend, Pandora was the first female human ever created. Pandora opened a jar, now called "Pandora's Box", that released the world's misfortunes, such as plague, crime, poverty, greed, and war, just to name a few.
 * Pandorite (and its relatives) are the Super Mario RPG equivalent to the Final Fantasy series Mimics, which are also monsters that disguise themselves as treasure chests. Both Super Mario RPG and the Final Fantasy series were developed by Square Enix.  In fact, Mimics appeared in the game Mario Hoops 3-on-3, a Mario-Final Fantasy crossover game.
 * If the player finds a roulette ? chest and gets three different icons, the last "monster chest" encountered will be battled again.