Jellivines aka Members of the Green Hive
These are sort of like primal zerg, so on their home planet they aren't organized into armies and generally only kill their neighbors in small skirmishes. But they would be challenging for any other sentient race to coexist with, and if dropped onto an alien planet they would be invasive (in the sense that annoying plants are invasive). Cannibalism is normal part of their diet, so squick warning for that I guess.
So anyway: Once upon a time an alien plant that closely resembled the type of succulent plants known as "stone plants" evolved to be a carnivorous plant called a stonesnap (xenolithops arpazo) by developing a sticky tentacle which could snap out and grab an insect, or on a larger plant could grab a rodent. These carnivorous plants evolved to become more and more animal-like until they were basically "plantimals", animals which retain the ability to photosynthesize and absorb water and nutrients from dirt, in addition to their more animal-like abilities to (in some life stages) eat with a mouth and walk on leg-like limbs to search for prey. These started living in social packs, and competition with both prey and other packs encouraged them to feed the lead pack member enough for that individual to have a bigger brain and more intelligence. Eventually these plantimals developed into a species that lived in hives of which the top caste of individuals are sentient. This species looks like a green jelly or slime from an RPG with several vines sprouting out of it, so humans have dubbed them Jellivines. Their name for themselves means something like "green hive members"., which might be translated as chloromelissi.
Modern Jellivines are a clear example of "ontology recapitulates phylogeny": they are birthed as a seed and sprout into an immobile, non-sentient "succulent plant" instar. These have no mouths and grow from photosynthesis and dirt alone; the other instars can subsist through periods of famine on sunlight, but only if they spend as few calories moving around as possible.
After 3 months of growth they progress from this first "succulent plant" instar to a second "carnivorous plant" instar. Specifically they sprout 2-4 vine tentacles and a mouth (which gives their mother the option to feed them if she has the resources to do so, and the will also feed themselves insects or small rodents or even small fish if they can catch them.) Second instars also gain the ability to retract their rootlets and slowly crawl short distances, if a sunnier spot or one with better soil is nearby. They are still non-sapient, with intelligence comparable to an insect or fish.
After at least 3 more months (depending on diet and environmental conditions) they develop into their third "plantimal" instar, which has 6-8 longer and stronger vine tentacles and has also developed eyes. At this point they are comparable to a mid-size mammal in intelligence; the most intelligent ones may learn to recognize a few spoken words. They aren't as mobile as their primitive ancestors, but have more fine motor control of their prehensile manipulative limbs (like octopus limbs only green and vine-like). They can quickly feed themselves if small prey wanders by, and if left unsupervised will happily eat smaller Jellivines. This isn't that surprising though, because young members of this species are actually the main cultivated "crop" of the intelligent adults. The average time from birth to the end of the third instar is about 1 year, but can vary from 9 months with abundant feeding and ideal temperatures to 3 years in extreme poor conditions. A queen jellivine can produce several pheromone pastes to be smeared on her hive members, one of which can freeze an individual in its current instar for a few months before it wears off and must be reapplied. This might be done if a hive already has all the warriors and juveniles it can support, or 2nd-instars intended to be eaten would be encouraged to remain in that form and get a bit larger rather than use up their accumulated calories developing into the third instar.
The fourth instar is the first sapient one, capable of full speech, and first fully mobile one, this could be called the "juvenile" or "worker" instar. They are gender-neutral, though they may feel puppy crushes. Socially they mainly try to be cute and helpful so older individuals will teach them life skills and share their food. Jellivines have a set of terms similar to kohai and senpai for juveniles who are adopted as apprentices by warriors, and the warriors doing the adopting.
After 1 year in ideal conditions or up to 4 years in bad conditions, they develop into the fifth instar, the male "warrior" instar. These are larger, stronger, and more armored than workers, and the largest members of a hive except for the queen. They hunt for the queen and themselves, and if there's any surplus they or the queen can choose which younger hive members to feed. They also defend their hive's territory, mate with the queen, and may transport queen-approved trade items to and from neighboring hives. The IQ of a warrior is about the same as a human, though the range is narrower: 80-120. Warriors remain warriors unless their queen dies or they leave their hive to start a new one. A queen can intentionally cause a warrior to mature into a queen with another of those pheromone pastes if she wants to support one of her heirs in starting a new hive.
So the sixth and final instar is the female "queen" instar, and there is normally only one queen per hive. Queens are the largest, and are mobile though slower and less agile than juveniles and males. They will occasionally travel to negotiate trades with neighbors or examine a new potential hive site, but when they do it's a slow procession guarded by warriors. Queens are regarded as being the only full citizens of their species, and all members of their hive are their property, that the queen has full rights to kill and eat them, to trade them to another queen, to mate with them, or to command them to do various work, including overseeing others. An individual warrior has the right to eat from his own kill and give some to any teammate warriors or apprentice juveniles before bringing it back to the hive, but once it's the hive's property the queen will eat as much as she wants and distribute the rest as she sees fit. Queens have an IQ in the 120-160 range, smarter than the average human though they are generally much less educated than any modern human, and they also don't reach the extremes of genius that humans generally do. They have the most advanced biological abilities of all the instars, including the ability to collect genetic samples from their food, and do minor manipulation on the genes of their seeds. They also have the pheromone abilities mentioned above, another pheromone paste which sterilizes a wound and encourages it to heal, and the ability to physically connect to an injured hive member and channel a healing super-nutrient blend to the injury site; this blend can be specialized for a bone injury, muscle injury, or skin injury. Jellivine bones (yes they do have some, though far fewer than humans) are made largely of silicon and as a result are somewhat brittle, and broken bones may require a queen to perform surgery to set the bone or amputate a limb that is too injured to repair.
