Here's why:

* Formation: Sedimentary rocks form from layers of sediment (like sand, mud, or organic matter) that accumulate and are compressed over time. This process is ideal for preserving the remains of organisms.

* Burial: The layers of sediment bury organisms quickly, protecting them from decay and weathering.

* Mineralization: Over time, the minerals in the surrounding sediment can seep into the buried remains, replacing the original material with rock-like substances. This creates a durable fossil.

While fossils can sometimes be found in metamorphic rocks (formed under high pressure and heat) or igneous rocks (formed from cooled magma or lava), these are far less common.