In the original Grandia, Mana Eggs can be found in the field screen or rewarded after certain boss battles. By trading Mana Eggs at stores, you can teach characters Magic skills. They can learn magical attributes including Fire, Wind, Water and Earth. Once you've learned certain elemental affinities, they can be combined to create other effects, which are Lightning, Blizzard, Forest and Explosion. It must be noted that these can't be taught by trading Mana Eggs in stores per se but rather levelling up Fire, Wind, Water or Earth will allow access to the greater magic. Once a Mana Egg is used, it can not be returned, though there are enough Mana Eggs throughout the game to teach Justin, Sue, Feena and Rapp each type of magic (excluding Fire for Feena and Rapp).