I remember watching this very peculiar British movie as a child called Quatermass and the Pit. It led me to view the first two in the series.
The serial versions are much different from the movie versions and more intense.
Catch them all if you can if you're a sci-fi buff.
The efx are kind of old now, but they older movies stood up better as stories than most modern sci-fi does...or at least the cheaper ones.