rocks!
there is all sorts of them
igneous
underground they are formed when the melted rock called magma deep within the earth becomes trapped in small pockets. as these pocks of magma slowly cool underground the magma becomes igneous rocks
sedimentary
sedimentary rock is formed by mineral and other materials sitting in water for an extremely long tome. while the minerals and the materials are in water they will have various things putting pressure on them
metamorphic
metamorphic rocks are rocks that have morphed into another kind of rock these rocks were once ingeous or sedimentary rocks the rocks are under tons and tons of pressure witch fosters heat build up and this causes them to change