The word Soft-shell is commonly used to describe animals or sea creatures that have a soft exterior, such as turtles or crabs. The antonyms for Soft-shell would include words that describe creatures with a hard exterior or those that are not soft. These antonyms could include terms such as hard-shelled, armored, tough, or rigid. An example of an animal with a hard-shell that is often used as an antonym to soft-shell crabs is a lobster. Other examples of antonyms for soft-shell could be found in the plant world, where soft-stemmed plants can be contrasted with plants that have woody stems or tough leaves.