Looks like someone built a homemade Alien xenomorph as a Halloween decoration. It’s not much to look at, but it moves, so it could be scary in the dark. But no…
In this Stan Winston Studio ALIENS test footage, James Cameron directs SWS puppeteers as they manipulate a rough "proof of concept" Alien Queen made out of garbage bags, foam core, and ski poles.
So what we are really seeing is the birth of the Alien queen! I did not know they did this, but I’m glad it’s available for all to see. I learned about it in the post 15 Secrets of the Hollywood Creature Feature at mental_floss.