自然 しぜん消滅 しょうめつじゃありませんでした
shizenshōmetsujārimasendeshita

Noun
Desu Copula

The polite, past negative form of 自然消滅

1. Wasn't naturally extinguished.; Didn't disappear on its own.; Wasn't naturally resolved.

Past/Perfective
Negative
Polite
Terminal Form