A few weeks ago, I listened to a discussion between Sir David Attenborough and Richard Dawkins produced for The Guardian UK. It wasn’t a particularly rigorous conversation, as Dawkins himself later commented, but it was interesting, wide-ranging, and introduced me to the concept of fractal animals.

Attenborough called them “thrilling” and though I can’t put my finger on why, I have to agree. Soft-bodied, organ-less, and immobile, they grew by creating branches upon branches in a self-similar, mathematical pattern. They expanded “like crystals of ice on your windowpane” and look oddly crafted, delicately sculpted fans and medallions wavering between a plant and animal identity. They were wonders.

They were also a dead-end. Fractal morphology backed evolution into a corner because it was based on the repetition of the same pattern. As Attenborough says, “You can’t develop a gut. You can’t do anything different. All you can do is that.” So, these first complex organisms, the most advanced life of a young, violent Earth, successful for millions of years, led essentially nowhere. Nothing currently living on Earth, as far as we can tell, is related to them.

There’s something compelling about them. Perhaps it’s because there’s always something beautiful about overt displays of mathematics in the forms of organic life. It feels like you’re seeing what’s behind the curtain. A stolen peek at the hidden machinery responsible for all the mystery.

Or maybe it’s because, at least for me, having never officially been taught evolution in public school, the idea that a species might just not work out was revelatory. Extinction is supposed to involve meteors, ice ages, over-hunting, or progression into a new species.  Catastrophe or reinvention. To simply fade away or be ineffective over the long haul seems sadly bureaucratic. Or are they more of a tragedy? A novel form of life, triumphant in their complexity, doomed to extinction by the characteristics that made them so successful.

Fractal animals are also an oblique reminder that we’re not living at the apex of things. We exist somewhere out in the middle of a rough continuum of life on this planet. It’s a strange sensation, to beobsessively aware of our own forward progress, but completely oblivious to the place of that progress in the admittedly impossible to grasp breadth of geologic time. I want to grasp it, but I can’t. Maybe it doesn’t matter. Or maybe grasping isn’t what matters. It’s enough to sense it out of the corner of our eye.

We are the winners, for the moment, of a long and spectacular process of trial and error. We belong here, but there’s no guarantee we always will.