Earthshine (item)

The Earthshine is an from Kingdom Hearts.

When Simba's world, Pride Lands, was destroyed, Simba, thanks to his powerful heart, didn't disappear, but was turned into a gem instead.

Leon was keeping the Earthshine until he gave it to Sora. Upon taking it to the Fairy Godmother, Sora learned the ability to summon Simba.

The fact of Leon having Simba's summon gem also references his connections with lions, most easily seen on his pendant, which depicts a lion, Griever.