Tesla's Sentry Mode uses the vehicle's cameras to record video of the surroundings while the vehicle is parked.
However, it didn't always have the familiar design it has now. It was originally depicted on the vehicle's display as HAL 9000 from the movie, 2001: A Space Odyssey.
Since then it has changed to be depicted as what appears to be the eye of a sentient sentry turret from the Valve video game Portal.
Easter Egg
Sentry Mode can be activated or disabled using voice commands, "Enable/Disable Sentry Mode" or "Turn Sentry Mode On/Off".
Voice commands "Keep Tesla Safe" or "Keep Summer Safe" can also enable Sentry Mode. The extra commands are a reference to a scene from season 2, episode 6 of Rick and Morty, entitled 'The Ricks Must Be Crazy,' where Rick instructs his vehicle to keep Morty's sister, Summer, safe while Rick and Morty venture into Rick's microverse car battery.
Elon Musk notably wore a Butterbot T-shirt to the 2018 Tesla Annual Shareholder's Meeting indicating his interest in the show.
