Here's a breakdown:

* Biogenic rocks are sedimentary rocks formed from the accumulation and lithification (hardening) of organic matter, like the remains of plants and animals.

* Examples:

* Coal: Formed from the remains of ancient trees and plants.

* Limestone: Formed from the shells of marine organisms, especially calcium carbonate.

* Chalk: A type of limestone formed from the microscopic skeletons of marine algae.

* Diatomite: Formed from the silica skeletons of diatoms (single-celled algae).

* Coquina: A type of limestone made up of broken shells.

These rocks are evidence of life on Earth and provide valuable information about past environments.