In what type of rock are most fossils found?

Most fossils are found in sedimentary rock because sedimentary rock preserves remains without the intense heat and pressure that commonly destroy them.

Sedimentary rocks form when particles such as sand, mud, mineral grains, or biological debris accumulate in layers and become compacted or cemented. An organism can be buried by this sediment before scavengers, bacteria, weathering, and erosion destroy it. Over time, its remains or impressions may become part of the rock.

Fossils are especially common in rocks formed in ancient seas, lakes, river floodplains, and other depositional environments. Hard parts such as shells, teeth, bones, and woody tissues fossilize more readily than soft tissues. Footprints, burrows, and feeding marks can also survive as trace fossils.

Igneous rocks form from molten material, while metamorphic rocks are altered by heat and pressure; both processes can erase fossil evidence. Rare exceptions exist, such as organisms preserved in volcanic ash, but sedimentary rock remains the standard fossil-bearing rock type.