The reason he died quickly was because he was just a weak kaiju. All he was was a mutated marine iguana, so he was bound to be weak.

How strong is Zilla?

Zilla is physically very weak. Its skin can be easily pierced by missiles and artillery and it lacks the strength to tear through suspension cables or knock over buildings. Just one blast of Godzilla's atomic breath was sufficient to destroy Zilla.

Is Zilla good or bad?

Zilla (in Japanese: ジラ, Jira), also known as American Godzilla, is the titular main antagonist in the 1998 film Godzilla, a recurring antagonist in the animated TV series sequel Godzilla: The Series as Cyber-Zilla, a minor antagonist in the 2004 film Godzilla: Final Wars, a major antagonist-turned-anti-hero in the ...