[Lawtan]

Sooo...
This is interesting

(Possible ick - it is a modular organism)

...I was looking up how the Thing could semi-realistically work. Short answer is that its proposed method - a parasitic plant/virus - couldn't, as things like plant cell walls make such things incompatible. And endoparasites (skin based) work more like warts for people (though they can force things like extra limbs on simpler creatures)...hmm...

Also, Underwater Robot repair snakes!