Hermit crab

The Hermit Crabs were seen wandering around the vicinity of the Northern Air Temple. Aang compared the creatures with the refugees living in the Northern Air Temple, saying, "Maybe you weren't born here, but you found this empty shell and made it your home". It seems fitting and is perhaps not coincidental that a nomadic animal by nature would live among the Air Nomads.

Anatomy
The Hermit Crab has two black beady eyes and is covered in a thick coat of white hair. It has six legs, two long black antennae, and a front pair of brown pincers, and it is most often found sheltering in slightly curved black and white shells.

Connection
Hermit Crabs look quite similar to their real world namesake, which dwell most often in abandoned conch shells. However, real world hermit crabs do not have fur. It is unknown what shell-bearing creature is leaving the used black and white shells behind.

Behavior
Hermit Crabs seem to prefer damp, dark places but are apparently quite adaptable to change. It is assumed that they change shells over their lifetime, like real world Hermit Crabs, but unlike real world Hermit Crabs, are considerably less flighty and are more accustomed to interaction with other species.

Trivia

 * In addition to the Hermit Crab, the fireflies are probably other creature that have survived to the genocide and have remained in the temple since then.