Harvest whale
From Halopedia, the Halo wiki
The Harvest Whale was a marine animal native to the planet Harvest.
It is rather more eel-like in appearance than normal and common Earth whales, and is unlikely to be a direct relative of Earth's mammalian variants.
When Harvest was glassed, the human population suffered tremendous loss, but the natural environment fared far worse. The entire ecosystem was turned to a toxic environment, leading many native species to die off or be slaughtered by the open toxic air. The Harvest Whales suffered such a fate. The fate of the Harvest Whales and the animals on the planet harvest is unknown, though most likely dead due to the environment.
its unknown weither or not it will be played in halo wars as docilal, or aggresive (attacking units that get too close to shores.)
