Behemoth, the Sea Monster (1959)
Behemoth, the Sea Monster (1959) is an American-British science-fiction film co-production. Originally a story about an amorphous blob of radiation, the script was changed at the distributor's insistence to a pastiche of The Beast from 20,000 Fathoms (1953), though elements of the original concept remain in the early parts of the film and in the "nuclear-breathing" power of the titular monster. The script was written by blacklisted author Daniel James under the name "Daniel Hyatt," with Eugène Lourié co-writing as well as directing. Released in the United States as The Giant Behemoth, the film starred Gene Evans and André Morell. It was distributed by Allied Artists Pictures.
More at Wikipedia.