いわむしじゃありませんでした
岩虫じゃありませんでした
iwamushija arimasendeshita

Noun
Desu Copula

The polite, past negative form of いわむし

1. It was not a rock worm.; I was not a rock worm.

Past/Perfective
Negative
Polite
Terminal Form
Usually Written in Kana