When exploring Moleville in Super Mario RPG, you’ll encounter a young mole girl who offers to trade her Shiny Stone for some fireworks. It’s not obvious straight away what the Shiny Stone is used for, though, so here’s what you need to know.
How to Use the Shiny Stone in Super Mario RPG
After trading Fireworks for the Shiny Stone in Moleville in Super Mario RPG, don’t sell the Shiny Stone. While it may appear useless, it has a specific function that most players will not want to miss out on: it unlocks a secret boss fight.
Progress through the story until you’ve collected the fifth Star and reached Monstro Town. Go to the Monstro Town Item Shop (the building with a wooden arch above the door; you can’t miss it), but interact with the black door to the left instead of going in. You’ll get a message that says the door has been “sealed.”
If you have the Shiny Stone in your possession, you’ll get another message that reads, “Look! The Shiny Stone is reacting! The seal has been broken!” and the door will open.
Go through the door to meet Super Mario RPG’s secret boss, Culex. It is a tough fight, so prepare first by leveling up or brute-forcing your way through it using items.
Who is Culex in Super Mario RPG?
If you’ve played Final Fantasy IV, you’ll immediately recognize the Culex boss theme music from the 1991 classic. Despite having the Final Fantasy music, looking like a 2D sprite ripped out of the game, and having a mechanic featuring crystals, Culex doesn’t actually feature in any Final Fantasy titles.
The original Super Mario RPG: Legend of the Seven Stars game for the Super Nintendo Entertainment System (SNES) was developed by Square (now known as Square Enix). And Culex is nothing more than a semi-subtle nod to the company’s popular Final Fantasy series.
Now that you know what to do with the Shiny Stone, there’s another video game, Easter Egg, to hunt down: Link from The Legend of Zelda makes a cameo in Super Mario RPG.