Revisiting Mr. Nobody

A family member was looking at old episodes of the 1960s Irwin Allen TV series Lost in Space and this inspired me to do the same, now that many can be found on the interweb.
I had vague but fond childhood memories of one called "My Friend, Mr. Nobody" and found it beguiling now, in spite of some Plan 9 cheesiness. (Spoilers for non-boomers)
It's a "Penny episode" (Penny is the Robinson middle child) which tended to be the more wistful and emotional ones, but rare, as the series gradually developed around the Will-Dr. Smith-Robot comedy act.
Rebuffed by Mom, who is helping oldest child Judy style her hair with some atomic contraption, and rebuffed by Dad, Don, and Will, who are busy being boys drilling for uranium, Penny wanders off into a glade with a bubbling spring and a cave. A male voice in the cave echoes her words and gradually learns speech from her.
Penny can't see the speaker and calls him "Mr. Nobody." He tells her he has existed for millions of years but does not know who he is.
The Robinson family humors her about the discovery, believing she has an imaginary friend.
Creepy stowaway Dr. Smith strings her along when he realizes she is bringing back diamonds from the cavern (gifts to her from her pal, who drops them from the ceiling). Smith hatches a plot to blast open the cave. Penny is inadvertently knocked unconscious and Mr. Nobody, believing her dead, comes to full roaring life as an Antimatter Being with the power to control wind and lightning. In the middle of a devastating attack on the Robinson spaceship, Penny revives and tells Mr. Nobody to desist.
At this point Mr. Nobody reaches his maturity and self-awareness and lifts off the planet in a beautiful, hypnotizing stellar cloud.
The moral of the story is "trust Penny." She is the only character in this episode with any heart or sense of the miraculous. Mom is overmedicated-seeming (poor June Lockhart had almost no lines), Judy a cipher, Don dumb enough to be manipulated by the Doc in his diamond scheme, Dad a distracted tinkerer, Will a condescending know-it-all who mocks Penny and observes that all women are weird. (Although he does make her a necklace because he feels bad that she's "pouting.")
Yet it is Penny who befriends the elemental being living under their noses, patiently teaches him speech, and helps him grow into full, mind-boggling consciousness. Her capacity for Platonic love and environmental awareness in the midst of a family of mindless consumers and earth-scorchers gives her near-mythic stature (predating the forest treks of Hayao Miyazaki's shojo -priestess Nausicaa by almost 20 years). Played by the sympathetic child actor Angela Cartwright she is a sweet, unerringly polite Everygirl who has a clue but can't get anyone to listen to her. She is the secret heart of the Robinson mission and the series. (So secret I only just realized it.)