Gossip Stone

Gossip Stones are objects found in Ocarina of Time, Majora's Mask, Phantom Hourglass, Spirit Tracks and Skyward Sword. They also appear in The Wind Waker, although in a different form.

These odd devices do and say different things depending on the game in which they appear. Gossip Stones can tell time, reveal information that they've heard, give helpful hints, or even reveal the locations of treasure chests.

According to the Ocarina of Time's in-game description, the statue speaks to Link by piercing into his mind.

Ocarina of Time
Link can speak to the Gossip Stones while wearing the Mask of Truth. Gossip Stones say a variety of things, some of which is helpful, some of which is typical conversational dialog. Their most defining characteristic though, is their reaction to certain stimuli, provided by Link himself. If Link sets a Bomb off near a Gossip Stone, it will flash blue and rocket to the sky. Likewise, these strange stones will spin around when exposed to Din's Fire, and flatten out if hit by the Megaton Hammer. If Link plays Zelda's Lullaby, Sun's Song or the Song of Storms near a Gossip Stone, it will release a fairy. The most common, and most useful, reaction is in response to a sword strike, in which the stone simply tells the time.

Ocarina of Time 3D
Similar versions of the Gossip Stones, known as Sheikah Stones, appear in Ocarina of Time 3D. Instead of telling the current time, Link can crawl inside these stones to trigger the Visions selection screen.

Majora's Mask
When the Gossip Stone is attacked by Link's sword, the screen will shake and the stone will make a high-pitched noise. It will then tell Link how many more hours remain until the Moon crashes into Termina. If Link speaks to the ones scattered all over Termina using the Mask of Truth, it will him give information regarding certain people or places.

Moon Gossip Stones
The Gossip Stones in the dungeons on the on the Moon give the locations to every normal mask in the game.

The Wind Waker
Link is given the Pirate's Charm by Tetra in The Wind Waker, and he uses it to communicate with Tetra and the King of Red Lions. It fulfills a similar purpose to the role played by Navi in Ocarina of Time. It is revealed later on that the Pirate's Charm is actually an enhanced version of the Gossip Stone made by the King of Hyrule himself.

Phantom Hourglass
In Phantom Hourglass, some Gossip Stones speak to Link without any conditions needing to be met, revealing hints that could become helpful later on. Other Gossip Stones, specifically the ones in dungeons, reveal how many Treasure Chests are left to discover. For a price of 20 Rupees, the stones show where those Treasure Chests are located.

On Harrow Island, a Gossip Stone near where Link docks the boat runs a Digging Game.

Spirit Tracks
Gossip Stones appear again in Spirit Tracks, but this time they seem to have a more feminine appearance. Normally they are unresponsive even when hit, but if the Song of Awakening is played nearby, they'll speak. Like in Phantom Hourglass, the Gossip Stones in dungeons reveal the amount of Treasure Chests on the floor they are currently in for a fee of 20 Rupees. Other Gossip Stones appear in several sanctuaries that reveal hints or other useful information. In Lost at Sea Station, there is a Gossip Stone that allows Link to enter the temple located in said station.

Skyward Sword
Gossip Stones (and similar Sheikah Stones) also appear in Skyward Sword. Gossip Stones only appear when Link plays his Goddess Harp in a telltale cloud of Blessed Butterflies. Most of them will give Link advice and a Treasure when he makes them appear.

One certain Gossip Stone in Skyloft, the Moonlight Merchant, will sell Link rare treasures for 100 or 200 rupees, which is usually much easier than finding them while adventuring. It can be found inside the Skyloft Waterfall Cave at night.

Ocarina of Time Manga
In the extra child chapters of the Ocarina of Time manga, Link activates a Gossip Stone by hitting it, which reveals that Mido still wets his bed and that the Deku Tree is troubled that he cannot scratch his own back.

Trivia

 * If a bomb is placed next to a Gossip Stone in Ocarina of Time or Majora's Mask, it will begin a countdown while changing colors and will shoot off like a rocket. By hitting them with the sword before they take off, they will stay the color they were. They can also be smashed into the ground using the Megaton Hammer or by pounding it as Goron Link. By using Din's Fire on one, the Stone will spin around and inexplicably stretch to double its height, soon snapping back to normal. Gossip Stones in Skyward Sword will also take off in rocket-fashion if a bomb detonates nearby, but will sprout from the ground again shortly afterward. They also sway when Link plays the Goddess's Harp near them.
 * In the German version, the hidden Gossip Stone behind the Deku Tree in Ocarina of Time says: "Man sagt, dass etwas Rätselhaftes passiert, wenn man während des Spiels den Resetknopf drückt." (They say, something mysterious will happen, if one presses the reset button while playing). Naturally, all that happens is a reset of the game. When the game was still recently released, many players got tricked and tried resetting the game and verify if anything had been altered in the game in any way.  This speculation has been confirmed as false shortly after.