Reikani

History
They originated in the Andromeda Galaxy, on a Ringworld's Habitat ring known as the Beacon of Knowledge. At some point the species which created them were dying off and eventually these beings took over the Ringworld using the corpses of their creators. This allowed them to spread to countless galaxies and worlds. While not much is known about them other than the fact that they take over dying or dead bodies of usually humanoid or other members of animilia families, it seems all of them have different motives.

Biology
Reikani take on the appearance of a scarab beetle, blue or gold depending if they're from the Andromeda Galaxy or from the Milky Way. They are a space faring species which are capable of surviving in the vacuum for thousands of years, though their true long span is unknown, the oldest Reikani was killed by a supernova at approximately ten thousand years old. They spend most of their time aimlessly roaming in space, unless they've reproduced on a planet. They seem to be able to survive in almost any type of atmosphere or the lack of one entirely. Their exoskeleton is stronger than metal which makes sure that anyone who bites into them will most definitely loose a tooth or bone trying to crush them. While entering an atmosphere will not kill them, they are hysterically afraid of being vaporized and tend to void it if at all possible. Though obviously they're not strong enough to resist the pull of gravity.

In order to further their survival, they are parasites which inhabit dying or dead individuals and modify them to fit their tastes, they are capable of subatomically manipulating these hosts, so no one host is the same. If the host dies, the parasite survives to live another day unless it was entire vaporized. However, if the parasite decides to leave the host, the original persona of the dead host has a chance of returning, or the parasite just leaves a copy of its own thoughts behind, allowing the host to become an individual on their own.

In order to dig into almost any surface their body works a lot like a molecular edged blade, allowing them to even burrow into that of a Kryptonians flesh with ease as well as many hard to break or cut materials. They are probably something you don't want to throw at someone you like. They'd probably make great assassins, if they were into that kind of thing.

Powers and Abilities
Longevity, they could potentially live on forever without being threatened by a natural death. Though they are often killed by catastrophes and murder. Limited Subatomic Manipulation, this power is temporarily available to the user everytime they first obtain a host. While it is limited, many times the individual whom is a host is no longer recognizable or has gained new features and traits.

Weaknesses

 * They have a genetically implanted phobia of being vaporized by atmospheric re-entry and direct contact with a star.
 * If they eat or burrow into Kryptonite, it will kill them, though they can sit on it and touch it without harm.
 * They will set metal detectors off, but they cannot be found by metal detectors or medical sensor systems.