The meteor crash is footage of the spaceship crash from It Came from Outer Space (1953) which Universal produced four years earlier.
Voice actor Paul Frees intones the ominous introductory narration. Frees was known for his villainous or serious voice portrayals, while fellow specialists Mel Blanc and Daws Butler provided more humorous characterizations.
The only movie monster to be a purely chemical process.
There actually are stones known as "trovants" in Romania, that grow, move, and even reproduce. They take in the minerals from the rain after each heavy downpour, which combine with the chemicals already existing in the rock to produce a reaction and pressure within that eventually causes the stone to grow and reproduce.