Antlers & Horns
Reindeer stags have magnificent antlers, topped only by moose in splendor. Ostensibly the antlers of reindeer and moose afford battle weapons for mating. Only rarely do the antlers actually encounter combat, and then for but the briefest spar, antler to antler.
Most often 2 males assess each other’s antlers. The 2 never touch. The one with the inferior headdress declines battle. Which is to say that a moose or reindeer has a mental image of how his antlers compare to another. How such self-assessment is made is not known.
Australian antlered flies confront each other head to head for determination of rank. The fly with the ample antlers almost always wins.
Rhinoceros beetles wield a forked horn on their heads. Horn size is highly variable: ranging from itty bitty bumps to a horn o’ plenty that runs 2/3rds the length of a male’s body. In any mating contest, the male with the bigger horn gets to mate.