Permineralization, or petrification, is one way that organisms are preserved as fossils. Highly porous materials like bones or wood can become petrified if they are buried quickly and thoroughly, before they start to decompose. Permineralized remains are the most common types of fossil found in the fossil NPS parks. Florissant Fossil Beds Nat. Monument has the most massive petrified fossils, the huge trunks of redwood trees. (Although there -are longer ones at Petrified Forest National Park, in Arizona).