Steller's sea cow

According to The I-Spyder Book of Earth Creatures, the Steller's sea cow — formally known as Hydrodamalis gigas — was a giant marine mammal typically hailing from around the area of the Commander Islands on Earth. They could be as much as eight metres long, and had "thick grey skin and small, bristly forelimbs".

They were driven to extinction by human hunting, with the last sighting on Earth being made in 1768.

They had an I-Spyder point value of 1000. (NSA: The Last Dodo)