Popobawas resemble large eagles, but are distinguished by having a longer beak, filled with serrations. They are also larger than most Terran eagles, having a 2.6 meter wingspan. But by far the strangest thing about them is their killing mechanism.
Between their legs is a large, sharp appendage. This was once thought to be their genitalia, but it is now known to be a keratinous spike, about 35 centimeters long. They use this to kill prey, as well as to fight rival males.
Popobawas are predators, feeding on smaller animals that inhabit Spine Island.
At the Thanatonian poles, a similar animal has been seen. It looks exactly like a popobawa, but it is only half the size, and the killing spike is only a fraction as long. This possible subspecies is also grey in color, as opposed to the black Spine Island popobawa.