Gills allow the fishes to breathe underwater. Scales help the fish in external environments due to waters. And find help balance the fish becoming more quicker. Mouth let’s fish eat small algae. And eyes help fish see electric move money from muscles to help see.
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.
Plants , Animals , & Fungi . Hope this helps you !