Once upon a time, there was an earthworm named Star. Star had a pretty good life. Sure, he had had a few close calls where he had almost gotten stepped on, but overall, his life was good. One day, Star went to go examine the local mine. He always liked seeing the miners bring back all sorts of colorful stones. 

He peered out over the ravine. He looked at the lava and water below and-

He fell. He was surrounded by darkness and didn't know where to go. He slid along for days, almost about to die, when the rock he was sliding over lit up in a bright red. In desperation, he nibbled at the red rock. Suddenly, his whole body lit up. He was no longer brown but a radiant green- white. He noticed a rip in his glowing skin, probably from a cut he had received from one of his journeys. Reddish powder dripped out.

Ever since, Star has lived in the caves, eating redstone to stay lit as he goes.