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// A Brief History of Terms: Scale 
// Story: Book 1 - The Behemoth came to Canterlot 
// by Equimorto 
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The term scale was first used by Princess Twilight. It was chosen for the shape of the objects, noticeably resembling that of a fish's scales, only larger. About the size of a hoof, largely flat, curved at the edges and with a slight but noticeable orientation very vaguely reminiscent of an arrowhead. Their surface smooth and reflective, oddly hard to get a proper grip on, giving almost the impression of being covered in oil despite being perfectly dry. Seemingly a muddy white in colour, if observed at the proper angle a scale would instead appear to present a rainbow-coloured exterior, either in the form of irregular rings spreading from the centre or as a scale-like pattern similar to that of snake skin.
Scales were proven to be hydrophobic, and showed similar properties with all sorts of fluids tested on them. They were impervious to all known sorts of corrosive substances, and did not cause any sort of chemical, physical or magical reaction when exposed to other elements. Any attempt to damage or break off fragments of one failed, from stress tests and drills to dragon fire and explosives. Magic in particular proved downright counterproductive, as the scales appeared to reflect the arcane energy directed towards them as a mirror reflects light.
The origin of the scales remains a purely theoretical matter. It is undoubted that their existence was a consequence of the Behemoth's arrival, but the exact mechanisms by which the two events are related have never been uncovered. They seemed to simply appear in Equestria, no trace of where they'd come from. For a while they remained as merely a small novelty, not particularly interesting compared to other more immediately pressing changes the Behemoth had brought. The effect they had on the creatures who found them was the only noteworthy thing about them, but even still it was a minor detail.
Of course, while seemingly the least important of the Behemoth's consequences, they were still one of its consequences nonetheless, and therefore something more than deserving to be studied and analysed. It was during this period of studying, after receiving one from a city with the explicit request to, that Princess Twilight came up with the term. That particular delivery was also the event that sparked the creation of the RHiSPaTS, though this is a matter best explored elsewhere. The origin of the term, beyond the simple matter of shape, lies in the possibility of the scales being or having been part of the Behemoth itself.
This is of course impossible to prove. The reason the assumption surfaced lies in the results of Princess Twilight's studies. She observed, comparing the tests run on the scales to the data recorded near the centre of Canterlot, that the results of said tests gave readings that matched those obtained from the Behemoth itself, only scaled down in intensity and range. Every pattern appeared to be exactly the same, and models showed that a sufficiently large amount of scales together could indeed lead to a replica of the Behemoth's signature graphs. Of course, this sparked great interest in further studying the scales themselves, as they could provide vital information on the Behemoth. It is through these further tests that the scales' more peculiar properties and uses came to be known.