Let's go crazy!
Myrmidons: The term is unjust and inaccurate, but as the name they give themselves is expressed as a complex taste and inside joke, "myrmidon" was the best humans who discovered them could do. The closest translation of their own "word" for their species may be "consensus".
They do not conform easily to human standards of taxonomy. A single myrmidon may appear as an amalgam of vegetable, fungal, arthropoid, and reptilian forms, and that is true to an extent, but that entity is really a combination megalopolis, spaceship, and giant mech for a colony - a family - of millions of mite-sized creatures. Humans compare these small beings to hive insects, but again such notions are only marginally true. The name "myrmidon" arose because their colony bodies often appear armor-plated by an amalgamate of secreted and acquired materials, sometimes woody, sometimes chitinous or even metallic, and because humans (the first to discover the species) assumed the small individual creatures were akin to army ants.
The true, tiny myrmidons are warm-blooded, one-eyed, and communicate with one another through a combination of chemistry and low-level telepathy. Anatomically they are diverse and specialized in function, though differentiation occurs by choice upon the end of an adolescent period, and not by genetic predetermination. They have a leadership hierarchy and ruling council rather than a single queen as humans might expect, and through their telepathy are able to quickly agree on and coordinate actions and reactions, so efficiently that most folks meeting a myrmidon colony would not distinguish it from a single "person". The colony as a whole interacts with the outside world, absorbing, distilling, and distributing memory and experience among its millions of inhabitants, much the way a single human brain works, but with more redundancy and in a less concentrated location.
The myrmidon "body" is a complex of gathered materials and secretions, similar to what both Earth snails and decorator crabs produce. Some of those materials are themselves living organisms, co-opted to produce food, warmth, and housing, to provide defense (hence the armor), and to create a scaffold on which to secure yet more material. The species became so skilled at creating nerve-like networks and physical joinery connecting these larger constructs that their colonies became mobile. As their intelligence evolved, they became experts at biology, chemistry, kinesiology, fluid dynamics, and medicine. The result is that a mature myrmidon colony is a semi-symbiotic, exothermic, walking city, roughly human in size and mass but not necessarily humanoid, with "organs" functioning as hospitals, factories, farms, and laboratories, and all with the same intellectual capacity and curiosity as most space-faring races.
Their evolution has guided them to this colony existence, and no individual or smallish group of myrmidons can survive long. Each colony is a single family unit, and their telepathy does not extend beyond those of their lines. Two myrmidon colonies must communicate as any two non-telepathic individuals must.
Individual reproduction is asexual and at-will, though typically in response to a colony need. Colony reproduction is a complicated, years-long endeavor begun when a colony reaches a certain population. To humans, it seems they "bud", with the bud dropping off and eventually growing into a new colony. The telepathic bond between the individuals of the bud and the mother colony fades, and eventually breaks. There is also a rare event when two colonies merge, though the specifics of this have never been determined by or revealed to non-myrmidons.
In game terms, a myrmidon colony is a single intelligence, usually curious, pacifist, and tending toward careers in exploration, the sciences, culture (which they find fascinating), and education. Colonies can reshape themselves given a day's dedicated effort, and therefore may be humanoid or not. They can (and often do) avail themselves of technology and habits of non-myrmidons, including wearing clothes, using tools, and producing physical speech thanks to specially-crafted "organs". A myrmidon colony may do virtually anything a human can do, but more slowly, and always acts last in any situation where initiative or turn order are required (unless utilizing special technology, such as a mechanical exosuit).
Because a colony of myrmidons is largely homogeneous, it is virtually impossible one can be fatally wounded by a single physical attack - attacks such as decapitation, stabbing, gunshots, lasers, etc. deal lower damage than usual and produce no special death effects. Other types of damage - fire, acid, electricity, etc. - deal normal damage. Most injected poisons have little effect, as do toxic or poisonous gases, because myrmidons can quickly cordon off affected areas. For similar reasons, a colony can survive for great lengths of time (though not indefinitely) in a vacuum or in the coldness of space, but does suffer damage initially. Myrmidons are especially vulnerable to telepathic attacks and nanotech.
Roleplaying notes: Myrmidons tend to refer to themselves as "we" and "us". They are ungendered, but may (or may not) adopt names, mannerisms, or habits of any gender or sex they've met. They often have difficulties mingling with other species due to not understanding constructs of culture and non-telepathic/non-chemical language, etc., but myrmidons are quick to adopt technologies and gear that help them better interact and integrate with other (much larger) species. Few take up the skills of combat or war, as conflict of this type is antithetical to their evolution, but they can be master strategists - and learn quickly.