The Creation of Geodes
There exists a creature that consumes food; just like us! However, unlike us, when this creature digests his food, his body compresses the nutrients into a beautiful little ball and sounds it with waste. The creature then poops out the entire nutrient/waste conglomerate, thus creating a beautiful geode, which i like to refer to as a poop stone!
However, because the creature never absorbs any nutrients (because he's always pooping them out) he eventually dies due to malnutrition. On the creatures last poop, instead of pooping out nutrients he poops out his soul into the poop stone and soon after dies. The soul will hibernate in the poop stone for however long it takes for someone or something to come along and crack the poop stone open. Then the creature is born again, like a phoenix, to continue the geode making cycle all over again!