period: Carboniferous (358.9-298.9 million years ago).

excavation site: Wałbrzych (Lower Silesia)

Calamites are tree-like equisetum plants which used to grow on the most wetland territories of carboniferous swamps. Their height reached even 10-20 m and its trunk had diameter of up to 1 m. Similarly as modern equisetums, they were characterised by segmental composition of shoots and whorled leaves arrangement. The trunks of older specimens were covered with thick bark and were empty inside. The specimen is an inner cast of the trunk – the so-called steinkern, most common type of fossil calamites. Its surface bears the traces of vertical vascular bundles and horizontal divide of the segments of the plant trunk.

The piece comes from the collection of Polish Academy of Sciences Museum of the Earth in Warsaw.