mossback

Etymology
From (in senses 1 (“person with old-fashioned views; one who is very conservative or reactionary”) and 2.3 (“fish that is large and old”) probably a variant of, which is attested earlier), alluding to someone or something that is so old or has remained so unmoving that it is as if moss has grown on them or it.

Sense 2.4 (“largemouth bass”) may refer to the back of the fish being a dark green colour.

Noun

 * 1)  A person who stayed hidden to evade conscription (especially by the ) during the American Civil War (1861–1865); a mossyback.
 * 2) A turtle that, because of its age, has a growth of algae on its back
 * 3) A common snapping turtle.
 * 4) A largemouth bass or.
 * 1) A turtle that, because of its age, has a growth of algae on its back
 * 2) A common snapping turtle.
 * 3) A largemouth bass or.
 * 1) A largemouth bass or.