testa, n. [L. testa a piece of burned clay, a broken piece of earthenware, a shell. See Test a cupel.].
The external hard or firm covering of many invertebrate animals. [1913 Webster]
" The test of crustaceans and insects is composed largely of chitin; in mollusks it is composed chiefly of calcium carbonate, and is called the shell."
[1913 Webster]
The outer integument of a seed; the episperm, or spermoderm. [1913 Webster]