The Rock Cycle is the transformation of rocks over time. The different types of rock that are in the cycle are metamorphic, sedimentary, and igneous. Igneous rocks are formed by the cooling of lava or magma, which is melted rock. Sedimentary rocks are tiny pieces of other rocks that are stuck together. Metamorphic rocks are existing rocks that have been put under extreme heat and pressure. The Rock Cycle does not go in one order. Different rock can change into all of the types of rocks.