Message in a Bottle

S2, E7: While exploring a now-dead planet O'Neill and the SG-1 team find an orb that sends out electromagnetic signals. They think it is a time capsule of some sort and are intrigued by its power source which seems to have lasted a millenia they bring it back through the Stargate. When Samantha Carter and Daniel Jackson begin their tests however the object begins to heat up and the team decides to send it back through the Stargate. The object however seems to have other plans. While it is brought to the Stargate it shoots bolts through the concrete walls floor and ceiling of the facility including one that pierces O'Neill's shoulder. Further investigation reveals that the object is sending out alien organism that is infecting people computers and the building itself. Attempts to destroy the orb only make it grow faster. As the computer screens go dark and the facilities self-destruct mechanism begins its countdown Carter suggests they let the organism take over O'Neill's body in the hope the orb will use him to communicate with them.