Hmm...haven't got any samples myself. Mind you, I think that the sounds that the aliens make in Aliens were created by speeding up a recording of an Elephant (but don't quote me on that!!!)
Bah! This is about the only teaser image I've seen of the Burke cocoon
I've heared loads of rumours that it was filmed, but they dropped it because the gestation period for the facehugger me ...