Alien parasitic worms that infest the brains of Humanoid bodies mutate their hosts into wormhost surgeons. These aberrant husks are obsessed with anatomical study and with finding new Humanoids to infest with larval worm slurry to propagate their kind. They can pass for ordinary people in most cases but must take care to hide their exposed brains and the wriggling worms within their flesh.

Secret.

Wormhost surgeons are drawn to seek out and infest sapient victims, so intelligent creatures with veiled minds slip beneath the surgeons’ notice.