6x14 - 3rd Rock from the Sun

Mary's mother Martha arrives in town and Dick decides to tell her what Mary really thinks of her - that she ruined her childhood. Angry, Martha tries to attack Dick and falls over, ending up in hospital. When Dick goes to visit, however, Martha tells him her side of the story, and a deeply moved Dick takes her side and promises to tend to her during her recovery. Meanwhile, Harry and Sally get a nasty surprise when throwing junk in the time space portal - a new alien.