Wikipedia
. Bog-wood, also known as abonos and morta, especially amongst pipesmokers, is a material from trees that have been buried in peat bogs and preserved from decay by the acidic and anaerobic bog conditions, sometimes for hundreds or even thousands of years. The wood is usually stained brown by tannins dissolved in the acidic water. Bog-wood represents the early stages in the fossilisation of wood, with further stages ultimately forming lignite and coal over a period of many millions of years. Bog-wood may come from any tree species naturally growing near or in bogs, including oak (Quercus – "bog oak"), pine ( Pinus), yew (Taxus), swamp cypress ( Taxodium) and kauri ( Agathis). Bog-wood is often removed from fields etc. and placed in clearance cairns. It is a rare form of timber that is "comparable to some of the world's most expensive tropical hardwoods".