1/ The Rock Cycle is a group of changes. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock
2/ Metamorphic rock is that was once one form of rock but has changed to the influence of heat, pressure, or some other passing through a liquid phase.

Lava the molten, fluid rock that issues from a volcano or volcanic vent.

Solidification to make solid into a hard or compact mass change from a liquid or gaseous to a solid form.

Igneous rocks can form beneath the Earth's surface, or at its surface, as lava.

Erosion earth's surface by the action of water, ice, wind.

Sediment to the bottom of a liquid dregs.

Compaction the act of compacting or the state of being compacted.

Cementation the act, process, or result of cementing.

Sedimentary rock that has formed through the deposition and solidification of sediment, especially sediment transported by water.

Weathering a weather strip.