Palantíri
The palantíri (sometimes translated as "Seeing Stones") were stones that could be used in communication with one another, and also to see many things across the face of the world.
The palantíri (sometimes translated as "Seeing Stones") were stones that could be used in communication with one another, and also to see many things across the face of the world. When its master looked in it, they could communicate with other Stones and anyone who might be looking into them. People of great power could manipulate the Stones to see virtually any part of the world.