Yes, clay is classified as a sedimentary rock. It originates from the weathering and erosion of rocks, where fine particles are formed as a result of chemical and physical processes. These tiny particles accumulate and can be compacted over time, leading to the formation of clay sediment.
The unique properties of clay, including its plasticity when wet and its hardness when fired, make it distinct from other sedimentary rocks. Furthermore, clay is often formed in environments such as rivers, lakes, and ocean beds, where it settles out of water and accumulates in layers. This layering and the fossils found within it are characteristics typical of sedimentary rocks.