Bird As Fish

I wrote something long and poetic on this topic, when I realized that I have no fucking clue. So I deleted it. Here's something more real. And I'm not even sure I'm asking the right questions...

Is it even real?

Is it just a biological sidenote?

Why do people spend so much time searching for it?

I know that, whether for right or for wrong, I'm pretty sure it doesn't exist, and I'm pretty sure that it's simply a biological phenomenon.