In their larval form, their limbs travel through space in translucent ships the size of basketballs. When approaching a planet, they use meteor showers to avoid detection. If detected, the ship self-destructs, creating an explosion large enough to destroy a city block.
Travelers stay hidden until they can invade a suitable host. They are a sadistic race that enjoy the pain and horror experienced by their host, as the trapped conscious is the object of ridicule and torture.
Its life cycle goes through four stages, of which only the earliest stage, the larval form, is mobile. It has appendages and hooks that it uses to settle on a victim after entering her through her mouth while she is sleeping or is paralyzed for whatever reason. Once inside, it goes through the next three states until it takes a shape to a brain that controls a network of whip-like filaments. These filaments interact with the nerves of the victim until, three days later, it is completely controlled. They also use these filaments as weapons, projecting from one hole a paralyzing tendril and another that extends to the heart of the victim to feed on their blood, which frequently leads them to store corpses to feed on them.
The filaments can also be used to animate memories of the dead and search for another host.