A migrating species of alien that travels in small groups called "pods". Not only are they migratory, but their primary method of travel is through witch space, leading many to give them the name "Witches". Some even refer to the pods as a "coven"
On their journey through space they will find themselves accruing quite a bit of space debris and must therefore stop for a bit of grooming, conducted with their many jelly-like tendrils.
Having traveled to and from such unfathomable distances, the debris collected on their shell is often quite rare. Some commanders have taken to mining the material, which is a win win. The Witches get assisted in grooming, and commanders get rare materials in exchange. It appears their shells withstand known weaponry, and their jelly-like tendrils are equally unaffected, leaving no risk of harming the Witch in the process. When the shell has been scrubbed, Witches give off a spray of color through the unblocked ventilation ports in their shell, something some commanders have taken to be a sign of gratitude.
There is a rumor that inside a Witches mouth is a wormhole, and if you fly inside you'll come out somewhere else. Wise commanders tell another rumor that that somewhere else is the butt.