It'd also be a good anecdote to explain why it's necessary to consider and develop new vocabularies to describe new media. Otherwise we'll end up thinking that rhinoceroses are unicorns.
Perhaps we already did.
Marco got it simple. He had heard about a unicorn, and saw an animal with one horn on the nose. He could inform his readers, however, that the unicorn was not in fact a beautiful, horse-like creature like most Europeans believed.
But the platypus? Nothing anything like it was described by anyone. They first called it watermole, I think, but had some trouble with the beak and the eggs.
These animals teach us two things: that we always understand the world from what we already know (that is the power of genre -- and of reusing theories and ideas); and that categories are the constructs of scientists, not nature. The whale doesn't care if its fish or mammal. The platypus doesn't care if it's mammal or bird. The only trouble is with our precious categories.
You see? It was not wrong for medieval scholars to call the whale a fish. Medieval monks cared about elements. If in water, fish. Makes a lot of sense to me. For all practical purposes, the whale is like a fish to most human beings.
(For people in Marco Polo's day, the Bible (including the Church traditions and annotations, anyway) listed all the animals God created. So the rhino had to be a unicorn.)
Only if it is purposeful to consider how it nurtures its offspring does it make sense to call the whale a mammal. It may be purposeful if you're a biologist, or perhaps if you want to say that whales are better than fish (smarter, more like people), so you can't kill them, but you can kill all the fish you want.
Maybe it isn't so bad "ending up thinking rhinoceroses are unicorns." They may very well be, until we have a good reason to think otherwise. I don't think games are narratives, but I think it is important to do the comparison.
For if we meet a "platypus," a text so strange it does not fit our perceptions of the world, then we have to search around for similarities in all directions before giving it a name. That name is meaningless anyway before we have formed an understanding of the object by comparisons. That's how our understanding works.