I concept designed all of the robots/creatures for the upcoming Screamers 2 film. this one has been shown in the trailer, so I'll put it up as a sneak peek.
My idea was to have this machine crawl up their throats, pull their face back and issue forth some sort of mechanical outer mandible, with an extendable inner tentacle. The practical was built by Adrian Morot's group, and I am sure it has been modified a bit from the original idea... mine was pretty involved.
this would allow for a prosthetic as well as cg additions. simple, but effective. the trailer: