Sometimes called "shape shifting", Metamorphosis is a term used to describe the ability of some characters to alter their physical structure into a variety of shapes and sizes. It differs from Transformation because the user is not limited to one form or a direct form.
In many cases, the shifter in question can alter their form to mimic the physical characteristics of people or animals. Some shape shifters can mimic another's form down to the molecular level, while others may be hampered by certain restrictions. Beast Boy for example, can shape-shift into any animal that he can think of, but his skin and/or fur and plumage will always be green in color. Clayface on the other hand, can imitate any living creature and can even compensate for finer details such as density and texture.