Name of Race: Ukalli
Pic/Description 
(I'm having a bit of trouble with my go-to character maker. Once I fix it I will make one, for now just description)
This androgynous specie stands at 1,40 to 1,65m when adult. This species overall appearance really alludes to an Amber "Stone", the "child" of this species is only composed of a sap-like substance and has trouble standing up or maneuvering objects. When they transform into adults their body gets an outward layer composed of the crystallized version o that substance, this takes away their goo-ish appearance and clumsy movements.

The species is partially see trough, becoming more solid if they are dehydrated. Its eyes are pupil-less and usually very round. It has no nose or ears but it does have a mouth. It has something that looks like hair on its head but in truth its something like human fat and acts as an emergency food, its placement is strategic since it keeps its core nervous system on its head. 

Its colors are usually blue, orange and magenta, having the eyes and "hair" being of stronger colors. Trough the body you can usually see little sparkling crystals, specially at night, and after a meal its common for this species to actually emit a faint light trough some glands of its body, this is a way it found to eliminate impurities when away from water-sources (It only prolongs the necessary bath though).  

Racial Characteristics:

The first thing one would probably notice when they meet a Ukalli (outside of the transparency) is that they are mute. This species developed nothing similar to vocal cords. This is probably the main reason why they are still on a hunter-gatherer lifestyle when other species are more developed, as communication used to be very hard (More on that in the bio)

Its skin might sound impressive when you compare it to the stone-like amber, but in truth its only a bit harder than the average skin and by no means as strong as leather. The real advantage is that due to their nature they can restore limbs, that is why the hair exists, a finger usually reforms in a week, a hand takes a month and further time resting to fully restore, an arm usually will be trouble for half a year. A beheading is most of the times fatal, the shock alone kills the nervous system, but, if by luck it survives unharmed its actually possible for the Ukalli to restore its body, quite easily if the enemy was foolish enough to leave the head close to the original body, when that is not the case the recovery is something that takes years and will either need the Ukalli to be very cunning or for a fellow tribefolk to find it.

Its vision is specialized for the night and will be ineffective on day, that doesn't mean they can see clearly on dark caves for example

Now that probably raise the question about their death. First and foremost, slashing in half and beheading is usually a good kill, just make sure to smash the head. Backstabbing is usually a bad idea unless you are stabbing the back of the head. About age, a "child" usually lives up to 26 years if it does not transform into an adult, the adult life expectancy depends on how good is its union (formed when two "childs" unit to become one adult, a lot on that later) a bad one results in a 10-20 extra time for the adult, a good one up to 40-50... Then there is the perfect unions, giving up to 70 extra years. The death happens because the neural system gets too damaged to function.

Finally, reproduction and "infancy". Long ago in its bio-history the Ukalli used to ingest chalk, salt and clay to create the layer they needed to move better, that however directly attacked its nervous system killing it soon, however a mutation happened and took the bonds of male and female a bit deeper. "Childs" (By no means infants, but the analogy works) are male and female, in the long past they used to reproduce like many other species, then however came the specialization, where the partners unite, literally, with one becoming the exterior layer and giving the other the chance to focus more on its metabolism and mental capability, thus why the species is androgynous. 

Race Bio: 

Living in wildest corner of the southern jungle the Ukalli live a nomadic life, their eyes are sensible to the sun so they prefer to avoid the midday, they have not developed shelter yet so they live inside the large tree hallows of the jungle. The bad unions and the Childs usually only stay on the jungle, collecting berries, herbs, insects, roots and vines for the tribe. The more apt go to the west and hunt on the plains, taking advantage of the darkness of the night.

For a long time each Ukalli lived alone, due to the union and the lack of communication they felt socially complete and saw no sense in uniting. The real reason why tribes started to show was the large preys found in the west, and the united tribe was the very recent act of a single perfectly united person (Ukallis have yet to develop names, for now I call it "Leader") its tribe had developed a signal language system pretty recently and that helped it to round up the other groups

Since an Adult Ukalli can produce something close to a child each two years completely alone when it is properly feed one would think their numbers would be high, but it isn't the case, Unions are scary for most of them, the idea of uniting minds is already uncanny but there is also a lot of prejudice over the one who becomes the external part of the body, as usually the adult figure will look more like the one who is inside, most chiefs outright forbid their childs from uniting as the "outer".

Techs: Right now they are very primitive, only having the basic use of stones.
On the other side they already have a form of proto-writing, symbols they carve on barks to show the others what activities must be done on the day, with enough time this should gradually evolve into a ideogram language. A really, long time.