Las Choyas Mine, "Coconut" Agates

Ok - are the mexican coconut geodes a type of fully-expanded thunderegg? There is some evidence to suggest that they are. They come from clay beds below rhyolite and it is suggested that they formed in rhyolite that flowed over something very wet, such as an aquifer. This provided large quantities of water vapour within the flow, inflating the cavities within the nodules to a degree of roundness. Most interestingly of all, very occasionally specimens show up that seem to have sparse traces of rhyolite shells. All this seems enough evidence to include them here.