There's nothing better than a good monster movie on a Saturday night:
In the Salton Sea, an underwater earthquake causes a crevice to open, releasing prehistoric giant mollusks. A rescue training parachute jump is conducted, but the patrol boat sent to pick up the jumper finds only a floating parachute. One sailor dives in but disappears. The other sailor screams in terror as something rises from the water.
A TV Guide review of The Monster That Challenged the World noted, "Fine special effects help this film along by adding an atmosphere of impending danger." A later review by author Dave Sindelar of Fantastic Film Musings and Ramblings, remarked: "For some reason, this fifties monster movie doesn't get much respect, but I think it holds up extraordinarily well. For one thing, I think the characters are unusually well drawn for this type of movie, and they're given a dimension and a sense of realness that adds a lot to the proceedings".
Respect for the "monster" also dominated a later review of The Monster That Challenged the World in the Video Movie Guide: "This late-1950s sci-fi programmer is set apart by only one thing: the giant monster, which is life-size (not a miniature), and given plenty of screen time."