In the latter stages of the Hundred Year War, a Fire Nation army factory near Jang Hui began polluting the surrounding river with its sludge waste. This resulted in vast ecological damage to the surrounding area including the clams.
Despite these changes, Xu still continued to sell these clams along with other mutated wildlife. A few of these creatures were presented to Team Avatar, who neglected buying them out of disgust.
Taken from the bottom of the filthy river bed, the clam is filled with a multitude of disgusting substances including dirt, seaweed, and dead bugs. It is a bivalved mollusk that is somewhat brown in color and has what appear to be blisters on its shells.
The clam is a mollusk, which is an invertebrate animal whose body is protected by two symmetrical shells. It has no brain or eyes, but has a set of kidneys, a heart, a mouth, and an anus. It feeds on plankton, and its natural predators are small sharks and squid.