Within the secret realm of the Wild Ant Tomb, apart from the Bloody Gobi, there are several areas - the barren, yellow sand, the ghostly rock forest, the ant tower plain and a swamp.
The last one sounds peculiar, how could there be a swamp in the desert? However, it exists because it connects to another secret realm, the Tidal Forest, rich with many trees and abundant water resources. Due to the substantial height difference in the terrain, a large amount of water cascades down forming waterfalls, endlessly reaching the Wild Ant Tomb secret realm.
But because of the limited water flow, it can't change the entire desert terrain and over time, it has turned part of the area into a swamp, inhabited by many pet beasts fond of the muddy and damp environment.