These charming stones are similar to the Moss bed specimens, though less distinctively mossy. They have a lower key to them - an understated beauty with some fascinating details. They have a smooth matrix forming lens-shaped eggs that are usually slightly off horizontal, as can be seen in the specimens below.
Flat Bed Thunderegg with All the Details - Streamers and Plume
Flat Bed Thunderegg with Red and Green Mineral
Flat Bed Thunderegg with Complex Core and Extraordinary Fine Details