Some common synonyms of metamorphose are convert, transfigure, transform, transmogrify, and transmute. While all these words mean "to change a thing into a different thing," metamorphose suggests an abrupt or startling change induced by or as if by magic or a supernatural power.

a complete change of physical form or substance. 2. a complete change of character, appearance, etc. 3. a person or thing that has undergone metamorphosis.

Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation.

Both are acceptable. There is a subtle* difference in meaning. So a butterfly is strictly speaking a metamorphosed caterpillar while a sculpture of a butterfly is metamorphosised stone.