When the Gliror first ventured beyond their homeworld, they discovered a species of violently territorial pseudo-arthropods. They weren’t edible and their shells were difficult to pierce, but they attacked anything that came within reach. So the Gliror started exterminating them wherever they were encountered. Alliance explorers would later follow in their hoofsteps, for the same reasons.
Alliance and Gliror xenobiologists have since catalogued dozens of genera with dozens more species and subspecies on hundreds of worlds. They’re all related, forming a single interstellar clade. The Gliror named them Rsthotho, which roughly translates to “giant ground wasp.” Explorers from the Alliance called them “crab scorpions.” These species and subspecies range in size from the size of a human finger to several tons.
All Rsthotho have ten limbs, with the two forward ones ending in powerful claws. These claws have extremely hard cutting edges capable of shearing through most materials and are used to excavate their nests. Crab scorpion mandibles are as hard and strong as their claws. These mandibles have even greater shear strength than their claws but are much smaller; if something gets within mandible reach it will be chopped to pieces, but its claws are much better suited to such tasks with their better reach and dexterity.
Their bodies are domed, much wider proportionally than a scorpion’s body, and they have long, dexterous tails. In most species, the tail ends with a stinger, although a few have knobby or spiked club tails. Rsthotho bodies are covered in clusters of small spines that act as tactile and air flow sensors. They also have four antennae arranged on their “foreheads,” one above and behind each of the four primary forward-facing eyes.
Ground wasp venom is necrotoxic in humans, Gliror, and most other known species. One Patrol medic described it as “brown recluse venom cut with battery acid.” Without immediate treatment, a human of Gliror will die if stung and in some cases the fleshy parts of the body will be reduced to a vile soup within hours. The stingers of most Rsthotho have the same mineral doping as their shells, allowing them to pierce even other Rsthotho exoskeletons, especially if they can hit a joint between plates. This includes most body armor commonly worn by Alliance, Gliror and Thabbo troops, and light powersuits have been breached by some of the largest specimens.
Rsthotho have extremely tough exoskeletons. A dog-sized species can often turn a handgun bullet, while some of the largest can absorb most of a military laser’s output. The chitin-analog of these shells is heavily doped with minerals. These minerals and the associated properties are directly linked to the local lithosphere. While mostly these are common minerals, some Rsthotho have been encountered with metal-impregnated exoskeletons. These examples have been known to possess exceptional resilience, much to the dismay of Alliance or Gliror troops or hunters trying to clear an infestation.
While not exclusive lithotrophs, the Rsthotho do gnaw rocks for their mineral content. They also eat other things. Their digestive systems are quite remarkable in their ability to derive nutrition from a wide variety of sources including plants and animals. If they kill a human or Gliror, often nothing is left of them, even their clothing and other possessions being consumed.
Most crab scorpion species are social, living in nests of a dozen to a hundred or more depending on species, although some are solitary. No species yet discovered is organized like a bee or ant colony with a reproductive queen and sterile workers. In all species, the females lay eggs and care for the young, with the males acting as guards and hunters.
With their natural tools and dietary requirements, Rsthotho prefer rocky areas for their nests. Since they’re burrowers, the definition of “rocky area” includes subterranean rock as well as cliff faces or mountainsides. A solitary crab scorpion will typically dig a burrow large enough to sleep in with some security, leaving only their antennae exposed to smell threats. The nests of social Rsthotho are, naturally, much larger. These nests often consist of a series of tangled tunnels and chambers, all crawling with ground wasps.
As stated before, Rsthotho are fiercely territorial. Anything coming into an area they have claimed will be attacked, killed, and eaten. If it puts up a fight, more ground wasps will arrive in short order to help. The combination of numbers and resilience makes stumbling across a Rsthotho nest a terrifying prospect even for a small military unit. Infantry are often overwhelmed in minutes or seconds, and even armored vehicles will eventually be torn to pieces by either a pile of smaller ground scorpions or a smaller group of larger ones; an angry two-ton Scorpius Rex can singlehandedly destroy a light tank or rip a powersuit in half, and several working together have been reported ripping the turrets from main battle tanks.
What happens if a Scorpius Rex’s stinger pierces the skin of an armored vehicle is the stuff of nightmares. Their venom is capable of melting human flesh on contact, and they can build up some pressure when angry enough.
The strangest thing about the Rsthotho is the timing of their arrival. As far as any xenopaleontologist can tell, they suddenly appeared on hundreds of worlds a few thousand years ago. One or more species, often of different genera, appear seemingly out of nowhere and form their own “society.” Almost invariably, they arrive at the same time as radiation signatures identical to those found in destroyed “Masters” facilities, suggesting some unknown connection between them.
This wouldn’t be so strange except for their intelligence, or rather lack thereof. While cunning predators, no Rsthotho has ever been observed using a tool, no matter how simple. Dissection of every species discovered has revealed neural structures akin to those of higher arthropods, at best on par with those of social insects like certain types of wasps. They are certainly not capable of building starships or other means of interstellar travel.
Alliance and Gliror researchers independently reached the same conclusion. Someone or something seeded the Rsthotho all over the known part of the Triangulum galaxy for some unknown reason. Whatever this reason was, it likely has to do with the fall of the “Masters” empire.