The scientific team has now discovered and studied a complete 385 million-year-old fossil forest. The Gilboa fossil forest in upstate New York's Catskill Mountains is often regarded as the "oldest fossil forest." Despite this, it has remained a myth according to scientific criteria. The latest discovery changes this assumption. Petrified wood is actually trees that have been transformed into stone by being soaked in acid. The acid dissolves any bone or hard tissue leaving only the soft tissue intact. Over time, minerals from the surrounding rock will leach into the acid solution turning the wood into stone. Petrified wood has many uses including building materials, paperweights, and jewelry. It can also be used as arrowheads due to its hardness. There are three main types of petrified wood: conifer, cycad, and angiosperm. Conifer petrified wood is by far the most common type found in nature and contains strands of cellulose with lignin still attached to some of the fibers. Coniferous trees such as pines, firs, and spruces produce wood that is relatively easy to transform into stone because there is a large amount of acid in their sap. This makes conifer petrified wood acidic. Cycads are tree species from the plant family Cycadaceae found in tropical regions around the world.