Shellites

The shellites were a race of turtles that lived on Ayr over a century ago. They were first discovered when some scientists cataloguing fauna on the continent noticed that a number of large turtle-like creatures would turn completely visible to the naked eye when moving to the light side of Ayr, where they would seemingly bend and refract the light around their shell in such a way as they'd be rendered invisible (but would still show up on thermal sensors). It was also noted, once the Grim Procession began it's march across the land, that shellites could enter the cursed mists and come out unscathed, although they would become temporarily visible even on the light side of Ayr, as their shells would glow for a few hours after passing through the mists. This same affect was observed after an Aether Storm had passed over.
Unfortunately for the shellites, they were hunted to extinction on the continent after the Erians told the denizens of Ayr about the true protective power of the shells of the poor creatures. In the time following the advent of Aether Storm and the Grim Procession, but before the Great Exodus, many in Kronos and outlying settlements would attach a fragment of the shellites' incredible shells to their doors as a protective charm.
A number of discoveries and revelations were made after the extinction of the shellite species. First, the shells weren't so much a protection, as they were a conduit and storage capacity for the force that would be come to known as Aether. If one leaves one of these shells outside during an Aether Storm, they will come back to find it glowing and charged with energy. It was then revealed that the Erians use these shells as a currency. Following the Great Exodus and overall destruction of both Kronos and Hyperion, the desparate populace of Ayr began to use these now extremely valuable shells as their primary form of currency (see Aether Coins). This was done for practical reasons, as it not only provided them a means of harvesting and storing energy, but also enabled desperately needed trade with the Erians to the south.
It has long been believed by many that the Erians fabricated the protective charm properties of shellite shells, in order to coerce the Ayrans to decimate the native population and give them a monopoly on "printing" of the now essential currency of both civilizations. Rumors have swirled for decades that the Erians have shellite breeding pairs on Erios, and use them to regulate currency and trade value in the regions.