A cystoid geode is now an extinct animal  that lived at the bottom of ancient seas 438 to 408 million years ago.  When a cystoid died, its body was covered with sand and sediment on the ocean floor and sometimes became fossilized.  When the cystoid became fossilized, it also became a rock with a hollow center geologists refer to as a geode. 
When the seas receded, the hollow cavity of the fossilized cystoid became filled with silica-rich ground water that caused quartz to form inside. 

Picture is representative of the specimen you will receive.  Each rock is unique and will vary in shape, size and appearance.  No two rocks will be exactly alike.

Origin: North America

• Every Cystoid Geode is different and will vary in size, shape, color, etc. 
• Average size is between 4″ to 6″