During the Silurian Period of the Paleozoic Era, 416 to 443 million years ago, marine animals called cystoid lived in ancient seas. Cystoids are a class of echinoderms – animals with hard exoskeletons that contain a high concentration of magnesium calcite. When a cystoid died, its appendages (brachioles) and stem quickly broke off. The body (or calyx) became covered by sand and sediment. Eventually, the internal organs decayed and silica replaced the magnesium calcite of the exoskeleton, leaving a quartz (silicon dioxide, SiO2) fossil with a hollow center. Over millions of years, the seas receded, leaving the fossils trapped below Earth’s surface. Ground water, rich with silica, filled the cavities of Cystoid fossils, causing quartz crystals to form. Origin: Morocco, Africa
Crack Open Cystoid Geodes – 4 Pack
- These rough looking, round shaped rocks may have a hollow center filled with beautiful quartz crystals. The only way to find out is to crack it open!
- 4 Moroccan Fossilized Cystoids & a bust bag included.
- Most are hollow, some are solid crystal. Everyone is unique and beautiful.
- Once sea creatures, these fossils could be up to 443 million years old!
- Be the first to see inside these prehistoric fossils!