Aliens Take Shape of What They Eat, Have Mouths With Rotating Blades

by Andi
(Romania)

I saw a movie when I was young that terrified me. It was about some human station in a desert like-planet where the sands lurched with bio-mechanic aliens that took the shape of whatever they ate.

After eating a young boy and 'stealing' his shape, the thing transformed, when attacking. It's mouth became rotating blades that made strange sounds.

I really want to know the name of this movie so I can look it up and see it again - at least to see if it's worth it. Thanks.