By the same token, I was fit for life on Mirabilis. The fact that I was also physically fit was just a nice bit of synchrony – not to mention novelty, in my case. I know what it is to be smart. I know what it is to be creative. I’ve never before felt strong, not like that. My body was powerful. My limbs were stocky. My thickened heart thudded boldly, a drumbeat deep and hale. My bones had likewise been altered for the task, dense enough to provide a more reliable framework. I wasn’t some sort of demigod or fairy-tale hero. I was simply me, reinforced.

I couldn’t wait to see what I could do with that.

I want you to picture the following creatures: a bat, a bird, and a bee. Specifically, picture their wings. All of these limbs serve the same purpose, but structurally, they’re quite different. Their wings, to put it simply, are not related to each other. In biology, this is called convergent evolution – two or more species independently developing similar features that weren’t present in their most recent common ancestor. Bats and bees can both fly, but this doesn’t mean they’re cousins. These creatures did not branch off from one airborne great-grandparent. Bats have a ground-dwelling lineage, and left their rodent-like family on the ground around fifty million years ago. Bees, on the other hand, are part of a very ancient line of flying insects that dates back to the Carboniferous Period – more than three hundred million years ago. Wildly divergent evolutionary paths, resulting in the same essential means of locomotion.

I find this concept so beautiful.

On Earth, the term invertebrate – anything without a spine – covers an astounding variety of body types. Spiders, sea hares, millipedes, cuttlefish, dragonflies, and clams all fit the bill. By comparison, vertebrates – snakes, zebras, condors, you and me – are tediously similar below the skin. The spine evolved only once in Earth history, and every being with a skeleton can trace itself back to the same root. We follow a basic template: a bilateral arrangement of skull, ribs, and pelvis, typically accompanied by four limbs. We have two eyes, one mouth, and a brain. The inner structure of our limbs is similarly predictable: one large upper bone, two parallel lower bones, the many little bones that form the wrist or ankle, and digits. We’re all working off of the same blueprint.

This is not the case on Mirabilis. Our time there was too short to do a full evolutionary study, but from the moment we touched down, it was obvious that life on that world had followed a very different trajectory. From observation alone (and with the mountain of caveats that implies), we hypothesise that on Mirabilis, spine-like structures independently evolved at least three times.

It’s impossible to predict, as progeny of Earth, how shocking a thing it is to walk into a tableau of vertebrates sporting different skeletal templates. We think we know what biological diversity is. Imagine standing in a wild place – let’s say a riparian meadow in a North American forest. Let’s also say that it’s late spring, and that you’re particularly lucky with the animals who have chosen to cross your path that day. It’d be only natural to marvel at the assortment before you – elk, bears, squirrels, hawks, salmon, salamanders, raccoons, turkeys, maybe even a bobcat. No two alike. Animals with physical differences so stark and overt, they’re one of the first things we teach to young children.

And yet, all of those creatures possess two eyes, one mouth, limbs with digits, and so on. They are, at the core, the same.

Jack won the dice roll on Mirabilis. It’s fortuitous that we lacked the live video coverage of the Apollo and Eridania missions, because the immortal words that flowed forth from mission specialist Jack Vo’s mouth as he became the first human to set foot on this new planet were: ‘What the fuck is that?’

We left that portion of audio out of our official report.

The worst part is, I can’t tell you what the fuck that was, in Jack’s eyes, because everything before us conjured the same question. I’m struggling to explain to you what we saw as we descended the ladder a few hours after we landed (we had to give the local residents some time to calm down and perhaps forget about the loud fiery thing that had landed in their midst). Every word in my vocabulary uses something from Earth as a reference point, and Mirabilis posed challenges for all of them.

Take, for starters, the ground cover. If I am to be a good scientist, I shouldn’t say we landed in grassland, because the stuff around our feet was not made of blade-like leaves peeling away from stems, but rather flexible spiralling stalks, each rising up to knee-height in a tight corkscrew (Spirasurculus oneillae). We learned later that these autotrophs (organisms that don’t need to consume a living source of energy, as animals do) do not photosynthesise at all. They chemosynthesise, like the creatures you find clinging to ocean vents back home. Spirasurculus suck the energy and nutrients they need from the groundwater below them. They grow upward not to reach for the sun, but to provide a landing place for a tiny flying creature we dubbed Murmurus voii, with which they are symbiotic. But, again, if I were to say we landed in ‘a field of curly plants’, this would lead you astray, because Spirasurculus are not plants. Yet ‘plant’ is the best word I have if I want to paint you a mental picture. Spiracurculus would mean nothing to you if I had not explained it, nor would the inaccessibly academic descriptor monocotoloid chemoautotroph. If I have to pause at every word to explain what it actually means, most of you would understandably wander off before I’d finished setting the scene.

So, for the moment, let’s sacrifice accuracy for the sake of impressionism: we landed in an alien ‘grassland’, surrounded by spindly ‘trees’ frocked with black ‘leaves’ – black, like all plant-approximates on Mirabilis, so as to absorb more of the subtle light. The hills undulated, pillow-like, so rounded they almost looked liquid. The sky was pale orange, an aesthetic I can only describe as ‘bright dusk’, despite it being midday. Due to the closeness of Mirabilis’ orbit, the sun was huge in the sky, yet not blinding. There was an ornamentation of other orbital bodies up there as well: a selection of Mirabilis’ seventeen moons, plus its sibling planets Opera and Votum, patiently waiting for us. We had landed in summer, mild and carefree. There were clouds, as an afterthought. There was a breeze, but barely. It was, to our human sensibilities, a perfect day.

The creatures before us seemed to agree.

I noticed their strength first. Everything on Mirabilis is robust, bold, built for heavy Gs and a cool sun. The imposing muscularity of this menagerie struck me immediately. My own supplemented strength felt like a cheap facsimile when faced with the genuine article.

The limbs were what I registered next, of which Mirabilis has three main phenotypes. First, the pairs of three: lumbering spotted behemoths with six pillared legs, and flap-like lips that rolled back in four directions to accommodate entire treetops. Pinch-faced herbivores with two pairs of on-pointe legs for locomotion, plus two intimidating scythe-shaped arms (primarily used for nothing more threatening than the alien equivalent of threshing wheat). Social flocks of tendril-covered fliers, each about the size of a skunk, held aloft by six wings that folded efficiently back whenever they left the air to wriggle through pondwater.

Next, the pairs of seven (seven!): a fleet-footed arboreal climber with long silky fur and a face like the ghost of a greyhound, breathtaking in its oddness and shocking in its beauty. A small group of split-snouted, hog-like scavengers in the midst of a violent argument over a fruiting shrub. A solitary smooth-skinned thing that has no Earthly equivalent, which everything else was avoiding or shouting at. It shivered through the shadows, watching the hog-bodies intensely but never making a move. It did not open its mouth, as we stood there, but I was afraid of whatever it held within.