Zygaena

Zygaena is a massive Shinheuh used as a "living arena" for team tests on the 21st Floor.

The creature is considered sacred by many occupying the 21F. It's appearance closely resembles that of a tortoise, with the exception of two blowholes in the center of it's belly and back, a long stingray-esque tail, two horns and a mouth full of sharp teeth. It periodically flips over, in order to "sunbathe". Whenever it surfaces, Zygaena will blow water through one of its blowholes. Its innards are accessible through the two blowholes, and provide more than sufficient space for a party (such as Ja Wangnan and his companions).

There is a special "jewel" that only grows inside of Jigena, which comes from the center of "Zygaena's Flower." It is extremely valuable, as it grows only inside of Zygaena, and is considered one of the best jewels due to its beautiful color. However this "jewel" also nutrition for it's babies as a result in order to protect this jewel value Yeon family had been harvesting these flowers.

Note* For some reason, Yuri seems to have an interest Zygaena's baby.