Testa is a term that refers to the outer layer of a seed or the shell that encases a nut. Synonyms that can be used for "testa" include seed coat, outer integument, husk, shell, hull, and skin. The seed coat is the outermost layer of a seed and acts as a protective shield against external factors such as moisture, pests, and physical damage. The husk, shell, and hull have a similar function, and they are typically discarded when the seeds or nuts are consumed. The skin is also a protective outer layer of some seeds and nuts, but it is edible and often left intact when being eaten.