sentences: metamorphic rocks do not contain fossils
docs: gneiss is metamorphic_rock. fossil is remains. slate is metamorphic_rock. marble is metamorphic_rock. schist is metamorphic_rock. amphibolite is metamorphic_rock. metamorphic_rock is rock. metamorphic_rock is stone. marlite is metamorphic_rock. marble is useful_metamorphic_rock.