Old sci-fi movie from back in the late 1950's?

That sounds like one of the Quatermass movies, give me a minute...

I think you're referring to "Quatermass And The Pit", which was a movie in 1967. It was also a short-lived BBC TV series in 1958. That's my best guess based on a recollection of the movie which I last viewed, probably 30 years ago. Good flick, as I recall. It's alternately titled "5,000,000 years to Earth", which is probably what's causing the confusion.

"20 Million Miles To Earth" was an early Ray Harryhausen movie with a stop-frame animated monster.

Sounds like : Quatermass & The Pit : Made 1967

Workers excavating at an underground station in London uncover the skeletal remains of ancient apes with large skulls. Further digging reveals what is at first believed to be an unexploded German bomb from World War II. Missile expert Colonel Breen is brought in to investigate, accompanied by Professor Bernard Quartermass. When the interior of the "missile" is exposed, a dead locust-like creature that resembles the devil is found. It is determined by Quartermass that these "locusts" are evil Martians who altered the brains of our simian ancestors to eventually lay claim to the Earth. When Quartermass's suspicion that the missile can reactivate the dormant evil in humans is confirmed, all hell breaks loose.

Watch the previous black and white Twilight Zone episodes and you will in all probability be waiting to discern each and all the outcomes out. back then it became into greater concerning the performing and plot than particular outcomes.