Piggyback Scorpion

Piggyback scorpions are small but deadly anthropods which live in close proximity to carrion snakes. While they produce their own toxin, they also feed off of prey and substances which are toxic to other species. Their favourite food is the poison produced by Mirror Lakes hedgehogs, but they are unable to extract the poison sac from the creatures themselves. Carrion snakes, whose favourite food is hedgehog minus the poison sac, have a special fang which allows them to do this. The scorpion is then able to feed on the leftovers.   Carrion snakes are not themselves poisonous, and that makes them vulnerable to larger prey. While the piggyback scorpions are significantly smaller, they are able to defend their snake companion using their sting. A sting from a piggyback scorpion will kill most species, including most sapients, and those it doesn't will at the least disable them for long enough for the two creatures to escape.   It took time for people to discover that piggyback scorpions and carrion snakes together play a vital role in the ecosystem. Hedgehog poison is one of the most potent poisons in nature and incredibly damaging if it leaks into the environment through the decomposition process. If a dead hedgehog is left to rot on farmland without the poison sac removed, it will not just ruin the crops but damage the soil to the point of nothing being able to be grown there for years.   It's possible for a person to extract the poison sac safely, but it's an incredibly difficult task which requires years of training to do so without accidentally splitting it. Relocating a dead hedgehog found on one's land is risky, as the spines are stiffer postmortum--able to penetrate through protective gloves--and you can't tell from looking at the body whether it released its poison prior to death, as the colour fades back to normal. As such, many farmers keep a carrion snake and piggyback scorpion to deal with any hedgehogs that die on their land, as the risk of being stung while handling the scorpion is considered the lesser one.   For giants and etertiles, piggyback scorpion toxin is only fatal in exceptionally high doses (i.e. multiple stings). For all other sapients, the sting is deadly unless immediate and effective treatment is administered. Anyone who keeps a scorpion to protect their land needs to keep personalised antidotes to hand and take them immediately upon being stung. Even after the mortal danger has passed, after-effects can linger for weeks.