What is the Eye of Bombasharna?

It is a strange thing, but references to the Eye of Bombasharna do not appear in the old books until after the Downfall of Numenor and the War of the Last Alliance; and few (if any) scholars in the North know of it. What little is known of the Eye is recorded in some Gondorian travel accounts from the early Third Age, kept in the great libraries of Osgiliath, Umbar, and to a lesser extent, Minas Ithil. By the middle of the Age, all those works were lost, with the possible exception of the Book of Pellardur in the Tower of the Moon; but that library is beyond the reach of simple scholars, and after T.A. 2002, it is lost to all the Free Folk.

Based off the historical record alone, it would seem the Eye of Bombasharna is not old, as artifacts go in Middle-earth; but this assumption must be quickly abandoned after only a cursory knowledge of its properties. Its form is that of an indestructable crystal sphere, in size similar to the Palantir of Annuminas: quite small, and thus easily transported, unlike the great Stones of Osgiliath and Amon Sul. Unlike the Palantiri, however, the Eye of Bombasharna is not clear, or dark: it resembles more a swirl of grey mist.

Moreover, the Eye does not seem to be an Eye at all, like the Palantiri; at least, not an eye for seeing in the normal sense. By all accounts, one cannot see anything simply by staring into the Eye, no matter for how long, or how strong the user's will may be.

I can only conclude that the Eye of Bombasharna is of similar workmanship to the Palantiri, which would make it an artifact of the First Age, and maybe of Valinor. But the Palantiri appear sparsely throughout the historical record, from Feanorian times in the First Age, to their status as heirlooms of Numenor in the Second Age, to their eventual long homes at various points in the Dunadan Kingdoms in Exile in the Third. The Eye is never in the historical record until the early Third Age, and yet it is surely as old as the Palantiri. What accounts for this?

Part of the reason, perhaps, is that the Eye has always been associated with the Far South, where scholars and scribes are few. But this conflicts somewhat with the scholarly tradition in the Harad, which saw several periods of "flowering" during the Second Age; moreover, the Numenoreans wrote extensively of the peoples and legends of the South during their periods of exploration and colonization during that Age. Furthermore, among many Numenorean scholar-adventurers (and most especially the more sorcerous Black Numenorean lords), the pursuit and discovery of items of Power was paramount.

What, then, accounts for the long absence of the Eye of Bombasharna from the annals of the South? Possibly the very thing that makes the Eye of such interest: its one great property, which sets it somewhat above the "simple" Seeing-stones of the North -- to go beyond mere observation of distant places and times, to actual teleportation, a thing unheard-of elsewhere in the legendarium of Middle-earth.