Asgard communicator
From The Stargate Omnipedia
A hand-held communications device utilized by the Asgard, for person-to-person and person-to-ship communications. The communicator resembles a smooth stone, and is held flat in the palm of the hand. It has no discernible buttons or switches.
KEY EPISODES
Fair Game - Thor gives a communicator to the SGC, so that they can communicate with him while his ship is in orbit.
Revelations - The team utilizes Asgard communicators when infiltrating Osiris' mothership in an attempt to rescue Thor.