sedimentary rock is a kind of rock & metamorphic rocks are formed by rocks being exposed to extreme heat and pressure ->  metamorphic rocks can be formed by sedimentary rocks being exposed to extreme heat and pressure  metamorphic rocks can be formed by sedimentary rocks being exposed to extreme heat and pressure & to be exposed to something means to be subjected to something ->  metamorphic rocks can be formed by sedimentary rocks being subjected to extreme heat and pressure  metamorphic rocks can be formed by sedimentary rocks being subjected to extreme heat and pressure & limestone is a kind of sedimentary rock ->  metamorphic rocks can be formed by limestone being subjected to extreme heat and pressure  metamorphic rocks can be formed by limestone being subjected to extreme heat and pressure & marble is a kind of metamorphic rock -> marble can be formed by limestone being subjected to extreme heat and pressure