These bubbles can originate from various sources such as volcanic lava, abandoned animal burrows, or decomposed tree roots. When an animal vacates its burrow or a tree root decays, it leaves behind a void surrounded by layers of sediment, which over time undergoes pressure-induced lithification, transforming the surrounding sediment into rock. Similar to Coconut Geodes formed by volcanic activity, mineral-rich water permeates the hardened bubble, allowing for the growth of crystals inside.