Drawing from the definition of "Structure", ULOs have the following qualities:
- The arrangement of and relations between the parts or elements of something complex. (n. structure)
- A building or other object constructed from several parts. (n. structure)
- The quality of being organized. (n. structure)
- An apparent 'Form Follows Function' that sets it apart from nearby elements or terrain.
- The object or cluster of objects resists definition as lunar geology.
