もくずかにじゃありませんでした
藻屑蟹じゃありませんでした
mokuzukanijārimasendeshita

Noun
Desu Copula

The polite, past negative form of もくずがに

1. Was not a seaweed crab.; Was not a zoea larva.

Past/Perfective
Negative
Polite
Terminal Form
Usually Written in Kana