Fighting Blood AgateGeodes are spherical to free form shaped rocks which begin formation as a hollow bubble inside a layer of rock. The bubble could be formed in the lava of a volcano or it could come from the hollow remains of animal burrows or tree roots. As an animal moves out of its burrow or a tree root dies, there remains a cavity surrounded by sediment hundreds of feet thick. The pressure of the sediment eventually causes the sediment around the void to turn into