Terra Wallop consists of two small terras joined together by a series of bridges. The terras are shaped like curled fists, one larger than the other, and are sparsely covered in foliage.
It is first seen in the episode "Calling All Domos" when Junko has a toothache and must travel to Terra Wallop to have his tooth pulled out. From this episode it is seen that the dentists on Terra Wallop are different from other dentists.
The second episode featuring Terra Wallop is "A Wallop For All Seasons", where it is seen that Wallops don't trust visitors, even if they're friends of a Wallop.