“...The agate cores which the thunderegg shells had been decomposed by wet enviroment, had been mistaken as mushroom fossils due to their mushroom-like shapes. I was able to correct this by showing how the thunderegg shells can be knocked off the agate cores to show the radiating crystal impressions. The agates are mostly featureless and often brown to orange colored. Few came with bandings and I have seen one with plume inclusions....”
 

writes Jeffrey Anderson on his website www.dwarvesearthtreasures.com