It's a 6-limbed multi-part casting, but with the miracle of blu-tac I have brought it to life. Here's a scale shot next to a Genestealer Magus and an early purestrain genestealer:
And are some more shots including close-ups of the head with tentacled mouth:
Here is the Ymgarl Genestealer as illustrated in the Rogue Trader rulebook:
A pretty close match wouldn't you agree? The head of the miniature, and particularly the tail, is more akin to the movie Alien figures, but it's essentially the same figure. Notice the miniature has the mouth tentacles of the illustration.
So, what do you think? I want one!