The premise of the movie from probably around the 60s or 70s I’m looking for is that astronauts bring back some material back from their mission, which escapes all safety protolols, multiplies, and is about to consume everyone in its path. Blob-like, but not “The Blob” (neither version). Not the Andromeda Strain (yeah, me loves those classics).
I only remember that the stuff they accidentally bring back, survives – I seem to remember a scene from near the end of the movie where a car drives off, the camera follows it, and then pans to a rock next to the road and you see a sizable speck of that stuff hanging there.
Overall residual feeling of that movie would probably be hard and nerve wracking suspense and some action, not comedy splatter teenie action.
That’s not it, sadly.
Can we rule out The Incredible Melting Man (1977)?