Answer:
Looks like a hippo crossed with a unicorn.
Tall when seated, short when standing.
I'm a red creature from the sea with large claws, or pincers, and I'm often boiled and served as an expensive dish at seafood restaurants.
What has armor but is not a knight, snaps but is not a twig, and is always at home even on the move?
This small creature kills even the largest one.
I can be found in water but never wet