遊泳 ゆうえう生物 せいぶつではありませんでした
yūeuseibutsudewārimasendeshita

Noun
Desu Copula

The polite, past negative form of 遊泳生物

1. Was not a swimming creature.; Was not a marine organism.

Past/Perfective
Negative
Polite
Formal Register