What type of rock forms from the accumulation of biological material over time?

Sedimentary rock forms from the accumulation of sediment, which can include biological material such as shells, plant debris, and other organic matter. Over time, these materials undergo processes such as compaction and cementation, eventually hardening into rock. This type of rock often contains fossils, providing valuable insights into past life and environmental conditions.

The other types of rocks do not primarily form from biological material. Intrusive rock, for example, originates from the cooling and solidification of magma beneath the Earth’s surface, while metamorphic rock is produced when existing rocks are subjected to high heat and pressure, transforming their structure and composition without melting them. Foliated rock is a specific type of metamorphic rock that exhibits a layered or banded appearance due to the alignment of minerals, but it also does not form from biological accumulation.