The true form of a Geode is a prismatic lump of living crystal.
Geodes are the recombined Elementals of Crystal, born from a combination of Air and Earth. Glowing shards of living rock, they have their own sentience and move by levitating several meters above the ground, hovering gently. Geodes are surprisingly intelligent but often quiet and reserved, and easy to mistake for inanimate beings.
They are capable of manipulating shards of crystalline quartz in a certain range around them, making them burst from the ground easily and shifting into the shapes that the Geode wishes. This has led to a practice similar to the encastration of Archons into buildings to protect them, in which a crystalline Geode can be 'set' into a wall or edifice and activate as soon as someone is in range to defend the building.
In a similar fashion to the Bladelings, Geodes are also prized as components for magical weapons made by the Alchemists. A shattered Geode is much weaker and unable to defend itself, and can then be reforged into a weapon to give it sentience.