The Blob (1958) starring Steve McQueen is the first of three films eventually made based on a creature that had its origins from somewhere in outerspace. It came to earth by way of a meteorite that split open after it crashes to earth.
The Blob is an amoeba-like creature that consumes living carbon-based life forms (namely people and animals). For every animal it consumes, it grows by that much more mass.
The only thing that can stop the Blob is cold, which was discovered in the climax o