Tullimonstrum gregarium, Tully Monster Pair 65de92f5c40dafb1acf9589def8d7888 formed from the silicon dioxide

formed from the silicon dioxide by natural irradiation

each specimen is dependent upon other minerals present in the locality at the time of fossilization

semi-translucent color makes it a unique curiosity among Tektites

scepter formations

Apophyllite frequently occurs in zeolite minerals in basalt

Tullimonstrum gregarium, Tully Monster Pair 65de92f5c40dafb1acf9589def8d7888 formed from the silicon dioxideTullimonstrum gregarium, popularly known as The Tully Monster, is the Illinois State Fossil & is perhaps one of the most mysterious fossils ever unearthed Age of the Tully Monster During the Pennsylvanian Period (roughly 307 million years ago), the land that is now Illinois lay near Earth's equator. Dense swamps, forested with primitive plants, covered much of western and central Illinois. In shallow seas nearby, the Tully monster swam along with