くろあたまうみへびじゃなかったです
黒頭海蛇じゃなかったです
kuroatamaumihebijanakattadesu

Noun
Desu Copula

The polite, past negative form of くろがしらうみへび

1. Wasn't a black-headed sea snake.

Past/Perfective
Negative
Polite
Casual Register
Usually Written in Kana