This episode is part one of a two-part episode.
In this episode, the sandkings are little creatures brought back from a Mars probe. The one who ultimately winds up as their owner is a scientist who has been studying them.
This is different than their origin in the book. In the book, they are bought by the main character from a mysterious stranger.
In the original book, the moral was a warning against greed and vanity. In this one, it was more about the dangers of scientific curiousity and pursuit of professional glory. Not just in typical measures, but when they become an obsession - they pose a danger to the scientist, and maybe ultimately... everybody.
Repeatedly, in this two part episode, the dangers to the environment that the scientist is exposing the whole earth two are touched upon in the course of the story. His reckless attitude stands in stark relief to that of his superiors who are taking no risks at all with the risky little prodigies they are the temporary stewards of.
I think the message the TV episode version of the story was pushing was not to let the reckless pursuit of some goal in the field of biology put the earth's environment at risk. Just what such a risk might be in real life, the viewer would have to decide for themselves.
The sandking creatures in this show are quite amazing, visually. It must have been done with some kind of CGI. The castles they build are very reminiscent of those described in the book.
This episode - both parts of it - are highly worth watching.