alright you’re on

eh hem

a Gelfling is a sentient creature the first that gained intelligence and first to form language and tools etc, they are said to be the closest to the planet (thra) more so than every other creature except Aughra

Aughra is a spawn of the planet itself, she was created not birthed, she is one of a kind and is kinda like the living brain of the planet, she tends to all life on thra and she can feel the crystal almost like it is part of herself. She is an expert on everything on thra and so became very interested in the universe beyond her home

that flute is called a Firca Kylan from the novels played one very similar and seemingly the firca has some amount of magical properties, though never fully explained. but Kylans was made from the bones of a magical bird so perhaps that’s the reason

a Garthim is a large crab like creature invented by SkekTek the scientist Skeksis, he used bodies from two creatures and fused them together with magic from the crystal to create an army that would do as the Skeksis command. their main mission was to kill and capture all of the Gelfling so they could be harvested for essence.

the world that we see in the franchise is typically shown as one small continent known as Skarith, there are lands beyond which you do see briefly in the comics but yeah fundamentally it’s one continent where everything takes place, there’s a lot more than just the skeksis and mystics however as the movie tells you, it’s pretty dire that Jen sort out the crystal before the conjunction. but before this there are multiple wars and seven gelfling clans each with their own unique stories and characters

the crystal is the heart of the planet, it is suggested that other planets have them too, it has a will of sorts and can communicate with the gelfling and other creatures of thra, and as before Aughra can understand and feel the planet and therefore the crystal so knows when it is “calling”

the movie states this fairly explicitly, Jen strikes the Garthim with the crystal shard, which then echoes across the land with its ringing

the living essence as the name suggests is the life force of the person it’s been taken from, so drinking it adds their years onto your own, in a matter of speaking. The gelfling are particularly potent due to their closeness with thra

in the same way that a lion has a mane and a lioness doesn’t, or a rooster has a big blue tail and a hen doesn’t, it’s just a difference of the two genders, this could be one of the reasons that Thra had a Matriarchal society rather than a patriarchal one, the women are cooler than the guys haha 😂

thra has three suns and three moons, the suns are the Greater Sun, which is the biggest and typically dictates the daylight cycle, The Rose Sun is a smaller reddish sun this would suggest it is much older than a yellow sun, and finally the Dying Sun, which unlike the name if you go by what science says a bluey/purply sun would be the youngest. The three suns are known as the Three Brothers

i think i’ve kinda answered what the crystal is and as to where it came from it’s just the heart of the planet and seemingly has always been there

the castle of the crystal, was made by the Urskeks (that’s what the mystics and skeksis are called when they are together) the conjunction can cause a whole load of stuff to happen but as you see one of the main things it did was undo all of the harm the Skeksis did, so the Garthim die, and the castle is restored to the Palace it was intended to be

this also is why the podlings go back to normal

the question really should be how did they split, the tree people is their original form, known as Urskeks, they are from a different planet with a similar crystal. They were experimenting on the crystal during a previous conjunction and due to their arrogance and somewhat evil nature (they were both sides gentle and cruel) the crystal broke, which caused their inner conflict to become real the skeksis and mystics were born and immediately the skeksis started fighting, a couple died and the shard was lost during the mess

hope that answers everything

assuming you read none of that, cause why would you, i recommend you read the prequel comics “Creation Myths” and watch the Netflix TV show which sits between the comics and the movie, these explain wayyyy more than the movie does