Netflix's 3 Body Problem is a show that leaves us with a lot of questions at the end of its first season. How different are Liu Cixin's books, upon which the show's based? What does the joke that Dr Ye Wenjie (Rosalind Chao) tells Saul Durand (Jovan Adepo) really mean?

But one of the biggest question marks has to be over the San-Ti themselves — the alien race making their slow and steady way to Earth in order to find a (gulp) new home. Although we hear them speaking in the show (via a human voice and in their VR game), we never actually see their true forms. So what do the creatures coming to wipe out the human race actually look like? What clues are there in the show, and in Cixin's novel trilogy?

The San-Ti are a technologically advanced alien race that live on a chaotic, dying world. Their home is part of a system of three suns, resulting in the planet experiencing extreme weather conditions whenever it enters more than one orbit at a time. During these events, known as "Chaotic Eras", the San-Ti have the ability to dehydrate themselves in order to enter a kind of hibernation. When the planet is stable again the surviving San-Ti can wake the others from hibernation by popping them into a body of water so that they come back to life.

Although various characters in 3 Body Problem speak with and interact with the San-Ti via a virtual reality game, their true forms are kept hidden.

In episode 5, Thomas Wade (Liam Cunningham) and Jin Cheng (Jess Hong) place on their alien VR headsets and are transported to a ruined desert world, where they're greeted by a warrior who appears as a representative for the San-Ti in the game world. When Wade asks who the warrior is, Jin responds, "An AI. Or one of them."

"They look like us?" asks Wade.

"We don't look anything like this," responds the warrior. "This is all for your benefit."

"What do you really look like?" asks Wade.

"You wouldn't like it," comes the reply.

This is one of the only clues we're given as to the San-Ti's true form. Basically, nothing like humans. So different, in fact, that even the sight of them might disturb us. We also know, from a conversation Mike Evans (Jonathan Pryce) has with the San-Ti in episode 4, that they communicate through thought. Maybe this means they don't have mouths, or perhaps any recognisable facial features at all?

The only other clue we have from the show is the dehydration element. The San-Ti are able to dehydrate and then rehydrate, which means they must have a physical body of some kind, right? Interestingly, there are actually some creatures on Earth that have a similar ability: Tardigrades, which are microscopic eight-legged creatures, are also able to survive for years in a state of suspended animation if they undergo extreme dehydration. Maybe the San-Ti look a bit like them?

If you're hoping for an easy answer in Cixin's novels, you're going to be disappointed. Although there are a few hints dropped here and there about the aliens (known as Trisolarans in the books), they're never described explicitly. The best clue we get in the books, just like in Season 1, is their ability to dehydrate.

It seems as though Cixin went with the philosophy that something imagined is often more mysterious than something clearly described.

But if we are going to imagine them, then maybe the humble Tardigrade is the best place to start.

How to watch: 3 Body Problem is now streaming on Netflix.