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Metamorphic
Igneous
Sedimentary
The names listed above are the 3 major rock category's, however one of them actually is great for preserving life and fossils. Sedimentary rock's are where fossils are usally found and there is a reason why fossils like sedimentary rocks. Lime stone is actually one of the best sedimentary rocks to find fossils in. The reason sedimentary rocks are so good for fossils is because the rock layers ontop of each other and builds for years traping and preserving what ever laid in the path long enough.
On the other hand fossils are almost never found in Igneous rocks but when they are found it is very rare. There are two types of Igneous rocks and they are intrusive and extrusive types. Intrusive rocks are made when deep inside the Earth magma is trapped, and molten rocks rise towards the surface and after million of years of the rocks cooling it finally solidifies and a intrusive igneous rock is born. Extrusive igneous rocks are really simple, they are often found near volcanoes, because they are made by lava or molten rock being really close to the surface or the earth or even on the surface. Then the molten rock or lava cools very quickly due to the cool temperatures of earths atmosphere and once it cools and solidifies a extrusive igneous rock is made.
Lastly there are metamorphic rocks. These rocks are not made but the transform already made igneous and sedimentary rocks. The processes of changing rocks into metamorphic rocks is due to extreme heat, pressure, and mineral fluids. To make a metamorphic rock either one of those process can happen or a combination of them can happen to make a igneous rock or sedimentary rock into a metamorphic rock. There are two different types of these rocks though and they are either foliated or non foliated metamorphic rocks. The two types are very simple and you can tell them apart by their appearance. Foliated rocks have sheet like structures, also hey reflect pressure direction that is applied to them. Non foliaded rocks do not have sheet like structures and the grains do not align when pressure is applied to these rocks, according to the USGS.
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