Spoon harvest

Four hundred years ago, give or take a handful of years (and that depended on whose hands you were looking at, as well), the civilisation known to historians as the Spoon somehow managed a mass destruction event.  They'd spread out a little from their home planet, colonising various asteroids and small moons in their system, and as far as we could tell, they'd destroyed anything small enough to be either blown up or put into a orbit that fell into their star.  Two moons were too large for that, and one of them had been dealt with quite effectively by redirecting a large asteroid onto a collision course with it.  The other moon still retained traces of their civilisation, mostly worked stone and some tiny caches of artefacts, but the big giveaway was really the lakes of metal where big things had been melted down to slag and left to harden.
The home planet had also been razed, but more had survived, as might be expected from a longer inhabited planet.  Sealed underground chambers had been found, some including mummified remains, and some containing unpleasant traps.  On a small island far away from the continental landmasses a village had been found, apparently overlooked when the main destruction had occurred.  And in orbit around the planet, seemingly forgotten, was a satellite network that still contained plenty of data.
We were investigating them, mostly on the pretext of finding out why they'd done it, and either preventing ourselves from doing it, or making sure we were only in the audience stands and not on the playing fields if we couldn't.  The majority of the research was taking place on and around the home planet, but there were teams sent out to other points of potential interest in the system.  We were a scouting party; our job was to look for things that were out-of-place and report back about them.
That is, out-of-place if you were a Spoon.  And that's what made the job so hard.
Briana pointed to a small hill.  She and I were stood on some kind of wide, shallow plain that had mountain ranges on two sides, shallow foothills on most of the a third, and kind of ran out into sand, and eventually a sea on all the remaining bits.  The mountains loomed, in the proper sense of the word, and gave anyone coming here to see them nightmares sooner or later.  This was the moon that had suffered the asteroid collision, though that was the other side to where we were, and so the atmosphere was thinner and shallower than its gravity could retain because much of it had been blown away, and the mountains were new.  They poked up well beyond the top of the atmosphere, and computer models I'd been running put it as touch and go as to whether they'd ever be back inside the atmosphere until they'd eroded.  There were no foothills on this side, just a sheer wall of rock that rose out of the ground up nearly a mile and a half before the first wrinkles and creases appeared.  In a few thousand years time, I thought, they'd be great for mountain climbing, but right now they were a lethal temptation.
"Do you think that's a man-made hill?" she said.  Her eyes were too large for her head, as were mine; we had had a number of small surgical alterations to make the job easier.  Everyone said that you could have them reversed at the end of the job, but I didn't know anyone but Auntie who'd survived to retirement, and she was now too fragile to risk that kind of surgery.  I looked, my overlarge eyes taking in more of the electromagnetic spectrum, and focused down from panoramic view to a tight view.  Muscles around my eyes tightened, and a second set that had taken me four months to learn how to use adjusted my corneas.  Effectively, I had a built-in zoom function, which was kind of cool.
"No," I said, shaking my head.  The atmosphere here was slightly viscous, though no-one had put forward an explanation for it yet, and it was like shaking my head underwater.  A little bit too slow.  "I think this is just the result of high-speed geology.  Water was thrown up when the mountains were, creating a glacier up near the top.  When the atmosphere thickened enough to reach it, it thawed out enough of the bottom to release the ice-mass, which then crashed down, skating down across this area and finally creating that sea."
"That's stupid," said Briana, which was her come-back to anything I said that she didn't like but didn't know how to argue.  "So where did the hill come from?"
"Rock and mud deposits either torn off by the glacier's descent, or left behind by the glacier as it melted."
"While it was rocketing down to the seashore?"
"Geologically fast," I said.  "It probably happened over a hundred years, which is bullet-fast for geology."
"Let's take a look anyway."
I shrugged; we'd not found anything interesting yet, and though I was pretty certain the hill was just terrain, it beat standing around looking for anomalies.
"Hey, what's that?"  Briana stopped, but I'd heard it too.  Something had tinkled.  We looked down, and Briana spotted it first: a slim metal straw caught half-under her boot.  She lifted her foot to see what we'd found, and it popped upright and started pushing out of the ground.
"Hey!"  She stepped back, and there was another tinkle.
We looked around; all the way behind us metallic straws were pushing their way out of the ground, rising eerily fast and swaying and clinking together as they did so.  We didn't need to say a word, we both just ran towards the hill.
When we reached it we looked back and saw that, like a field of wheat, there was now a field of swaying, clinking metal straws, each nearly ten feet high.  The edge of the field was perhaps a minute's walk from us, and seemed to be fixed.  Caught up near the tops of the straws were small rocks and clumps of dirt, some neatly skewered through.
"What the hell?" I said, and I could see from Briana's face that she'd been thinking exactly the same thing.
"Some kind of harvest crop?" she said.
Maybe.  Maybe we'd just found a Spoon harvest.