* Sedimentary rocks form from the accumulation and cementation of sediments, which can include the remains of organisms. These remains can be preserved as fossils.

* Igneous rocks form from the cooling and solidification of magma or lava. The intense heat involved in their formation destroys any existing fossils.

* Metamorphic rocks form when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are transformed by heat and pressure. While some fossils might survive the metamorphosis, they are often distorted or destroyed.

Therefore, sedimentary rocks are the most likely to contain fossils.