Magma Ball

The Magma Ball is a Rare item gained at Magma Rock. It is described as "a glowing, red ball of volanic rock." Near the end of the dungeon, around the time you gain the Blaze Psynergy, there is a room with lava and platforms and it "erupts", spewing out many flaming rocks. The rock on the top left contains the Magma Ball. When Felix takes the Magma Ball from it, the rock loses its heat source and freezes. It can be placed into the cannon to break down the wall in Loho, prompting the dwarves to install the cannon onto your ship. Then at the entrance to the Northern Reaches, the Magma Ball and cannon are used to break the wall of ice and allow you to enter the game's final region, containing Prox and Mars Lighthouse at the northern edge of the shrinking Weyard. Afterwards it can be sold for some quick cash, as it has served its use. Note that if you sold it too early by accident, you can still buy it back as an Artifact in any town's Item Shop for 800 coins.