Message in a Bottle (S02E07)

While exploring a now-dead planet, Col. Jack 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 millennium. They bring it back through the stargate for further study. When Capt. Samantha Carter and Dr. 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, apparently has other plans: As it is carried to the gate room, it shoots bolts of energy through the concrete walls, floor and ceiling of the facility. One energy-pulse pierces O'Neill's shoulder. Further investigation reveals that the object is releasing an 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 facility's self-destruct mechanism begins its countdown, Carter suggests they let the organism take over O'Neill's body in the hope that the orb will use him to communicate with them, and negotiate a non-disastrous end to the crisis. (Metro-Goldwyn-Mayer (MGM))