A shell is considered as biotic (living) because it is a hard, rigid covering of many animals such as snail, sepia, pila, turtles, sea urchins. A shell is protective outer layer of these soft bodied animals.
it is considered to be biotic because it is known to be a protector for the living thing. it covers the living things skin to keep itself protected. if you need this answer more in depth it’s on quizlet!
