I remember seeing a preview of that movie when I was a little kid. That would have been in the 1950's, so it would probably have been about the time it came out. We didn't have tv yet (too far out in the country to pick up the big city stations), so my parents must have taken me to a children's movie at the theater. They were probably less careful about previews back then.
Anyhow, I remember being absolutely terrified, mostly (I think) of a shot of a headless body. (I guess the crab monsters prefered the tastiest parts and left the rest....) Had nightmares for a week. But I could never remember the name of the movie. I've even tried to find it a few times over the years but I didn't have a clue about the title.
Now I'll have to see if it's streaming somewhere.