A Hellion is around 200m long when fully extended. However, the majority of the time its tentacles and prostheses are tucked up together around its body, so it appears like a reptilian 10m long only.
The Hellion possesses thick fullerite armour and repulsor sheets, making it highly resistant to damage. They can launch their tentacles out from their body at extreme speed, reaching out to full stretch within 0.02 seconds. These then anchor onto prey and the Hellion pulls itself onto the object.
There are also many sensory and weapon prostheses, mounted on stalks. The function of only a few of these is known, such as their camera eyes, highplasma torches, repulsor cutters, and spike launchers.
Hellions eat both metallic and organic material. They have been seen feeding off other Vesanians and also attacking ships.
The presence of large amounts of metal drives them into a feeding frenzy.
Whether Hellions are sapient is under debate. When within atmospheres, they have been recorded to speak, sometimes in recognisable languages. However, these sentences do not fit the context- some believe they are parroting the last words of previous victims.