せぐろうみへびじゃなかったです
背黒海蛇じゃなかったです
seguro umihebijanakattadesu

Noun
Desu Copula

The polite, past negative form of せぐろうみへび

1. Wasn't a black sea snake.

Past/Perfective
Negative
Polite
Casual Register
Usually Written in Kana