こだまかいじゃなかったです
小玉貝じゃなかったです
kodama kaijanakattadesu

Noun
Desu Copula

The polite, past negative form of こたまがい

1. Wasn't a small jade shell.; Wasn't a small shellfish.

Past/Perfective
Negative
Polite
Casual Register
Usually Written in Kana