My theory is that Alduin is the Stone of Snow-Throat.

-A Tower's locus of creation lies in its Stone. Alduin was cast in Time, creating a wound on Snow-Throat where the Elder Scroll was used.
-Alduin was designed partly with a "meteor" aesthetic.
-The Meteor is an echo of the Zero-Stone, which lay inside the Ur-Tower which fell from the sky.

That's all I have. Just a theory I had after talking to Paarthurnax on my latest game.

My other theory:

There isn't one. The devs never made one, and MK hasn't yet thought of one.

*addendum*
Dragon Breaks occur when Towers are screwed with. The Tongues screwed with Alduin, and Time was fractured. The Time wound could have been caused just as well by the use of an Elder Scroll, but when looked at from the schema of my theory, it fits too.

I think it must be Arngeir's kidney stone.

I always thought it was Alduin too, well that or the Nords but I just don't see how an entire race can be a stone... It's hard enough to believe that the Khajiit or even the Mane is a stone, but then add the Nords to it as well?

Don't know what that rambling is about, but I agree... Alduin is the only real candidate that I can think of.

I never liked the theory that races can be Stones. All the Towers and Stones are echoes of the first ones. It sounds stupid, but I expect all Towers to be vaguely Tower shaped or anologous to towers, therefore we have towering mountains, trees, and golems. Has there ever been a physical description of Zero-Stone? How do we know it wasn't Akatosh's heart, just as Red Tower's Stone was the Heart of Lorkhan, and Brass Tower's Stone was Talos' heart, and White Gold Tower's Stone was Alessia's heart/soul along with the souls of all the Emperors'?

When the Snow Tower lies sundered, kingless, bleeding

Alduin is kinda a king, had himself an empire 'n' all?

Ah, but High King, or "King" Ysmir?

http://imperial-library.info/content/talos-mistake Who is named, "crowned" Ysmir, by the keepers of the tower?

http://imperial-library.info/content/fight-one-eating-birth-dagon

Who is killed on top of the tower, so that the world can continue? Who is involved? http://imperial-library.info/content/five-songs-king-wulfharth

Seeing the strength of King Wulfharth, Orkey summoned the ghost of Alduin Time-Eater again. Nearly every Nord was eaten down to six years old. Boy Wulfharth pleaded to Shor, the dead Chieftain of the Gods, to help his people. Shor's own ghost then fought the Time-Eater on the spirit plane, as he did at the beginning of time, and he won, and Orkey's folk, the Orcs, were ruined. As Boy Wulfharth watched the battle in the sky he learned a new thu'um, What Happens When You Shake the Dragon Just So.

Well, clearly it doesn't have one because having stones in your throat is bad. Like a bloody polyp from Oblivion.

But really, now, Snow-Throat is pretty much a center of power(?) for Kyne (association with Paarthurnax as given by the emblems, communion-worship of the Greybeards, throat of the world, perhaps other references as well) and I don't think that should go out the window in this discussion. For Alduin to be the stone just seems... odd. Considering that, according to the emblems, it was Paarthurnax Kyne dug. Not that that's very reliable, of course. Still, Alduin is the bloody world-eater. Does it make sense for him to help hold up the Mundus? Although... considering... Towers prolly don't act identically to one another. Too simple. It's not so much the Mundus that they're holding up as much as a certain interpretation of the Mundus. We saw the Ayleids vanish after White-Gold was appropriated, after all. If Alduin built(?) the Throat of the World or merely destroyed its original stone and substituted himself, it'd explain why the pattern of dragons vanished from the world when he was time-blitzed; his interpretation was no longer being upheld. I suppose during the interim, then, Paarthurnax would have been acting as stone and... yeah. But still, I don't really like this.

Eh, I should give a disclaimer here: I mostly think that this idea of Towers requiring stones is... well, crap.

EDIT: Contents blitzed for irrelevancy. Thanks for the source, Chaplain.

http://www.imperial-library.info/content/nu-mantia-intercept

If "King" Ysmir is the stone, does Dovahkiin become the stone after the Greybeards recognize you as Ysmir? I mean, the universe might as well end if you die during a playthrough.

How do you know it doesn't?

Nu-Hatta may be wrong Chaplain, such is the nature of TES.

High King. I like the connotations of when there is no High King, not only is Skyrim weakened politically (warfare, civil war, lack of unity and leadership) but metaphysically as well. It places greater emphasis on the Moot, with the need for a leader who is legitimate and supported by all the Holds/people.

http://www.uesp.net/wiki/Lore:Skyrim%27s_Rule, coupled with the dialogue in-game, claiming for generations, that the High King has been an Imperial Puppet, something that drains away metaphysical depth, to the point it seems unlikely that the position would be snow-throat's "stone".

I believe Skyrim itself might be the Snow Tower.

Skyrim is sundered, kingless, and bleeding, so yeah, that could be it.

Has the Eye of Magnus been ruled out as a candidate for the stone? Saarthal is a good ways away from High Hrothgar, but it's similar conceptually to the Heart of Lorkhan and the origin of the Eye isn't really well explained, otherwise.

I disagree, but all I'm basing it on is that the towers are, as Chaplain said, anologous to the originals, and as you have Red mountain it makes more sense to me that the Throat of the World is the tower.

Perhaps we're approaching this from the wrong angle. Who have been the controllers of Snow-Throat? From the earliest point that we can assume, the dragons, specifically Alduin. The effect? Dragons held dominion over man and Skyrim almost as gods and they held a monopoly over the Thu'um. Next comes pre-Jurgen Windcaller Paarthurnax. This is the Paarthurnax of the Rebellion, who taught man not only the Voice, but also how to pour their emotions and fury to possess the world. This philosophy and form of the Thu'um overwhelms and overtakes the Dragons. Then the 1st Battle of Red Mountain happens and Jurgen Windcaller comes back chastened and the Nordic philosophy of strength of Thu'um will possess the world. He and Paarthurnax (presumably) start from the ground up and create the Way of the Voice and the Greybeards, teaching restraint and proper application of the Thu'um, not to possess the world, but to perfect their self. Nowadays, Snow-throat is controlled by the Greybeards, who is headed by Paarthurnax.

Are there any through-line symbols here? There's the Thu'um and it's use, but I'd say that that's more an effect of controlling Snow-throat. There's breath and Kyne and words, though excepting one of them, that's not a very tangible symbol. But, perhaps that's all that you need to control Snow-throat. After all, Snow-throat effectively became Human-controlled when they spoke "Joor Zah Frul" at it's summit, declaring to the world that mortality and the finite have come to stay. Perhaps Snow-throat doesn't have/need a stone, that all you need to control it is strength of will, surety of Voice, and a certain philosophy you can express through it.

Thu'um, issuing from the Throat of the World? That would make a lot of sense. And Thu'um is another element Talos used in working his mythopoeic knot.

I don't quite understand the objections to Skyrim, or rather it's people, being the Tower. High Hrothgar, or the Throat of the World, isn't sundered or bleeding, they are kingless only by dint of being in Skyrim, and even if the world is about to end, Aegnir pretty much says it's business as usual for them. Would perhaps make sense if you had to obey the Blades, but seeing that you have free choice in that matter, can't see how the prophecy applies, whereas it does to the province and people.

When Nu-Hatta listed towers, one of them he called "Snow-Throat".

I think there may be four linked entities: the Stone, the Tower, the Land, and the People. There seems to be a pattern of Towers dominating the landscape of each Imperial province, and having a spiritual significance.

To put it a different (better?) way, Towers hold up certain qualities of Mundus (land, people, whatever pattern the controller favors) as well as just keeping the whole thing going. Not 'as well'; there is no division of function. The Towers hold up the Mundus because their controllers favor the Mundus. ( "http://www.imperial-library.info/content/nu-mantia-intercept" ) Even Alduin did, I suppose, while he was in power. If you go by things as they are presented in Skyrim. MD, you pretty much pointed out the trend (as others may have done). But that's not really the point of this topic, so, eh.

On Stones: if we go by http://www.imperial-library.info/content/nu-mantia-intercept,

"Let the Elders acknowledge this truth: every Tower bears its Stone. The impossipoint of the Convention was the first, though another bears the true title of First Stone."

However, also,

"They are magical and physical echoes of the Ur-Tower, Ada-mantia. Ada-mantia was the first spike of unassailable reality in the Dawn, otherwise called the Zero Stone."

This seems to imply that Ada-mantia itself is the Zero Stone. That, or the Dawn itself is being referred to as the Zero Stone, but I think that seems unreasonable. The earlier quote names the impossipoint of Convention itself as the Zero Stone. There seems to be some dissonance here, unless we view that Ada-mantia, Convention, and Zero Stone as one entity. I suppose it is named Stone after the fact because it is the foundation of Mundus' existence.

"The powers also created Red Tower and the First Stone. This allowed the Mundus to exist without the full presence of the divine."

Nu-Hatta makes no mention of Lorkhan's heart, only Red Mountain and its First Stone. Or, Red Mountain the First Stone, if the implications noted above carry any weight by metaphysical echo. Perhaps the physical differentiation between Red Mountain and Lorkhan's Heart was only due to the Dwemeri tonal machinations, which would explain why it vanished when those enchantments were destroyed. Perhaps the echo just slipped a bit away from the Zeroth Stone, I don't know. To my mind, there is a serious disconnect in the guy's words here, because the way this one is worded implies a difference between the stone and the tower. Convention and Ada-mantia are the Zero Stone, but Red Tower and First Stone are not the same thing? Only way I think to explain it is echo-slippage; inexact reenactments.

Anyway, my point is that the document (seemingly) contradicts itself unless Towers and Stones are the same, and that metaphysical echoes need not be exact; i.e., not every Tower needs an explicit stone, and Snow Throat probably does not have one as a separate entity. I'm pretty sure we only know of 'Stones' for Red Mountain and White-Gold, anyway. I will submit a few quick theories; that stones are constructs more associated with controlling a Tower than its function; that Stone refers to the reality the Tower upholds; and that's all I've got for now.

EDIT: The Wheel on its side is the Tower. A Tower on its side is a point; a Stone. Different ways of looking at the same thing.