Destination Inner Space (1966)

Strange goings on at the site of an experimental underwater laboratory as a mysterious object of unknown origin is detected in the area. A group of researchers investigate and come face to face with the object, a large automated extraterrestrial probe. They board the craft and discover a small object at first considered to be some sort of instrument package, which they take back to the lab for closer inspection. It is then that events take a turn for the worse.