I think this must have appeared around the early to middle 1970s, and was serialised in a weekly UK comic (sorry, can't remember which one).
The story was set in a small town, where some aliens invaded. They had three legs, and their arms ended in suckers rather than hands (bit like the end of the non-deadly arm on a Dalek). If any human got too close, then blew some kind of large bubble from the suckers that settled over the person, trapping them inside.
Don't remember much more of it than that, other that at the very end, some common threat caused the humans and aliens to work together (a young boy was the hero as I remember). Right at the end, the boy held one of the alien's suckers and shouted triumphantly "You did it!" to which the alien replied (in a thought rather than speech bubble) "No, we did it."
Anyone any ideas? Thanks