* Formation: Igneous rocks are formed from the cooling and solidification of molten rock (magma or lava). This intense heat and pressure would completely destroy any pre-existing organic matter.

* Fossils require preservation: Fossils form when organisms are buried in sediment and protected from decomposition. The sediment eventually turns into sedimentary rock, preserving the remains.

To summarize:

* Igneous rocks form from heat and molten rock.

* Fossils form from the preservation of organic matter in sediment.

It's important to remember that fossils are found primarily in sedimentary rocks.