Which feature is shown only by higher invertebrates, as compared to lower invertebrates?
bilateral symmetry
true coelom
three germ layers

metamorphism is the change of minerals or geologic texture (distinct arrangement of minerals) in pre-existing rocks (protoliths), without the protolith melting into liquid magma (a solid-state change). the change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. i hoped i !