The “cockroaches” of the coal forest.
Insect fossils are rare because its body is generally too fragile to resist the fossilization conditions. This is not the case of these specimens who have been preserved in the muddy sediments of the Carboniferous swampy forest, about 300 million years ago (S. Pedro da Cova and Pejão coal mines).
The fossils exhibited are wings of insects alike the actually cockroaches and among them several new species were defined in articles published in “Comunicacoes dos Serv. Geol. Portugal”.